If the determinant of the matrix is zero, the code does some very
dubious things which happen to fail in the right way mostly by accident.
This happens to break #24247, but it's clear that checking for a zero
determinant makes sense anyway.

URL: https://trac.sagemath.org/24450
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): David Roe

Let `MIPVariable` not inherit from `Element` but `SageObject`. The only
reason it used to be this way is to be able to multiply variables with
scalars that can be dealt with in other ways. The previous inheritance
scheme used the old parent framework that we try to get rid of.

See also the task ticket: #21380

URL: https://trac.sagemath.org/21353
Reported by: vdelecroix
Ticket author(s): Vincent Delecroix, Travis Scrimshaw
Reviewer(s): Vincent Delecroix, Travis Scrimshaw

There is a nth_root method defined on univariate polynomial (via Newton
method)
{{{
sage: R.<x> = QQ[]
sage: ((1 + x - x^2)**5).nth_root(5)
-x^2 + x + 1
}}}
We provide a more general implementation in a new method
`_nth_root_series` that compute the series expansion of the n-th root
for univariate polynomials. Using it we implement straightforward
`nth_root` for univariate (Laurent) power series.

This branch will not consider support for `extend=True` (see this
[[https://groups.google.com/forum/#!topic/sage-devel/ijYyZ4IduF0|sage-
devel thread]]). When `extend=True` the method will simply raise a
`NotImplementedError` while waiting for Puiseux series in Sage (see
#4618).

On multi-variate polynomials there is also a `nth_root` method but which
is implemented via factorization (sic)! The multivariate case should
just call the univariate case with appropriate variable ordering. This
will be dealt with in another ticket.

URL: https://trac.sagemath.org/10720
Reported by: pernici
Ticket author(s): Mario Pernici, Vincent Delecroix
Reviewer(s): Sébastien Labbé

Indirectly found by a `random_expr()` run:
{{{
sage: exp_polar(arcsec(jacobi_sn(1.1*I*x, x)))

...doesn't return. When stopped we find ourselves in Maxima:

/home/ralf/sage/src/sage/symbolic/function.pyx in
sage.symbolic.function.BuiltinFunction.__call__
(build/cythonized/sage/symbolic/function.cpp:11630)()
    992             res = self._evalf_try_(*args)
    993             if res is None:
--> 994                 res = super(BuiltinFunction, self).__call__(
    995                         *args, coerce=coerce, hold=hold)
    996

/home/ralf/sage/src/sage/symbolic/function.pyx in
sage.symbolic.function.Function.__call__
(build/cythonized/sage/symbolic/function.cpp:6670)()
    486             res = g_function_evalv(self._serial, vec, hold)
    487         elif self._nargs == 1:
--> 488             res = g_function_eval1(self._serial,
    489                     (<Expression>args[0])._gobj, hold)
    490         elif self._nargs == 2:

/home/ralf/sage/src/sage/symbolic/function.pyx in
sage.symbolic.function.BuiltinFunction._evalf_or_eval_
(build/cythonized/sage/symbolic/function.cpp:12909)()
   1080         res = self._evalf_try_(*args)
   1081         if res is None:
-> 1082             return self._eval0_(*args)
   1083         else:
   1084             return res

/home/ralf/sage/local/lib/python2.7/site-packages/sage/functions/log.pyc
in _eval_(self, z)
   1066         """
   1067         if (isinstance(z, Expression)
-> 1068             and bool(-const_pi < z.imag_part() <= const_pi)):
   1069             return exp(z)
   1070         else:

/home/ralf/sage/src/sage/symbolic/expression.pyx in
sage.symbolic.expression.Expression.__nonzero__
(build/cythonized/sage/symbolic/expression.cpp:19904)()
   2835             # lot of basic Sage objects can't be put into
maxima.
   2836             from sage.symbolic.relation import
test_relation_maxima
-> 2837             return test_relation_maxima(self)
   2838
   2839         self_is_zero = self._gobj.is_zero()

/home/ralf/sage/local/lib/python2.7/site-
packages/sage/symbolic/relation.pyc in test_relation_maxima(relation)
    514     else: # operator is < or > or <= or >=, which Maxima handles
fine
    515         try:
--> 516             s = m.parent()._eval_line('is (%s)'%repr(m))
    517         except TypeError:
    518             raise ValueError("unable to evaluate the predicate
'%s'" % repr(relation))

/home/ralf/sage/local/lib/python2.7/site-
packages/sage/interfaces/maxima_lib.pyc in _eval_line(self, line,
locals, reformat, **kwds)
    450                     line = line[ind_semi+1:]
    451                 if statement:
--> 452                     result = ((result + '\n') if result else '')
+ max_to_string(maxima_eval("#$%s$"%statement))
    453             else:
    454                 statement = line[:ind_dollar]

/home/ralf/sage/src/sage/libs/ecl.pyx in
sage.libs.ecl.EclObject.__call__
(build/cythonized/sage/libs/ecl.c:8466)()
    800         """
    801         lispargs = EclObject(list(args))
--> 802         return
ecl_wrap(ecl_safe_apply(self.obj,(<EclObject>lispargs).obj))
    803
    804     def __richcmp__(left, right, int op):

/home/ralf/sage/src/sage/libs/ecl.pyx in sage.libs.ecl.ecl_safe_apply
(build/cythonized/sage/libs/ecl.c:6082)()
    373     if ecl_nvalues > 1:
    374         s = si_coerce_to_base_string(ecl_values(1))
--> 375         raise RuntimeError("ECL says:
"+ecl_base_string_pointer_safe(s))
    376     else:
    377         return ecl_values(0)

RuntimeError: ECL says: Console interrupt.
}}}
The Maxima problem should be reported elsewhere. The bug in Sage is that
the `exp_polar` code uses `bool(-const_pi < z.imag_part() <= const_pi)`
to check the argument is in an interval but the argument can have
symbols and in that case a proof is attempted unnecessarily.

The ticket should change the `exp_polar` code such that the proof is
only attempted with nonsymbolic argument.

URL: https://trac.sagemath.org/24441
Reported by: rws
Ticket author(s): Ralf Stephan
Reviewer(s): Travis Scrimshaw

Since it is usually infeasible to compute all reduced words of a
permutation, an iterator may be more convenient.

As a side effect, the performance is also a bit better.  Old:
{{{
sage: %timeit [len(pi.reduced_words()) for pi in Permutations(6)]
1 loop, best of 3: 42.3 s per loop
sage: version()
'SageMath version 8.2.beta1, Release Date: 2017-12-22'
}}}

New:
{{{
sage: %timeit [len(pi.reduced_words()) for pi in Permutations(6)]
1 loop, best of 3: 4.9 s per loop
}}}

URL: https://trac.sagemath.org/24434
Reported by: mantepse
Ticket author(s): Martin Rubey
Reviewer(s): Darij Grinberg, Travis Scrimshaw

Merge branch 'public/categoires/some_cleanup-21353' of git://trac.sagemath.org/sage into public/categoires/some_cleanup-21353

The following all give errors:
{{{
sage: gcd(I-I*x, x^2-1)
sage: gcd(I+I*x, x^2-1)
sage: alg = SR(QQbar(sqrt(2)+I*sqrt(3)))
sage: gcd(alg+alg*x, x^2-1)
sage: gcd(alg-alg*x, x^2-1)
sage: sqrt2 = SR(QQbar(sqrt(2)))
sage: gcd(sqrt2+sqrt2*x, x^2-1)
sage: gcd(sqrt2-sqrt2*x, x^2-1)
}}}
This is fixed in Pynac master and should be doctested here.

Note that although Singular supports algebraic GCD Pynac uses Singular
only in rational mode. Use a dedicated polynomial ring instead of
symbolics if you want algebraic GCD.

URL: https://trac.sagemath.org/23845
Reported by: rws
Ticket author(s): Ralf Stephan
Reviewer(s): Travis Scrimshaw

On sage 8.0
{{{
sage: (x^2/(1+x)).coefficients()
Segmentation fault (core dumped)
}}}

gdb shows that this is an infinite recursion in the Pynac library:
{{{
#0  GiNaC::add::integer_content (this=0x4095f00) at normal.cpp:95
#1  0x00007fff50051660 in GiNaC::ex::integer_content
(this=this@entry=0x7fffff7ff410) at normal.cpp:81
#2  0x00007fff50076fdc in GiNaC::power::eval (this=0x7fffff800040,
level=<optimized out>) at power.cpp:674
#3  0x00007fff4ff9b29e in GiNaC::ex::construct_from_basic (other=...) at
ex.cpp:691
#4  0x00007fff50041ac3 in ex (other=..., this=0x7fffff800030) at
ex.h:305
#5  GiNaC::mul::combine_ex_with_coeff_to_pair (this=0x40961a0, e=...,
c=...) at mul.cpp:1228
#6  0x00007fff4ffa3084 in GiNaC::expairseq::evalchildren
(this=this@entry=0x40961a0, level=1) at expairseq.cpp:1647
#7  0x00007fff50047390 in GiNaC::mul::eval (this=0x40961a0,
level=<optimized out>) at mul.cpp:666
#8  0x00007fff4ff9b29e in GiNaC::ex::construct_from_basic (other=...) at
ex.cpp:691
#9  0x00007fff50049ff6 in ex (other=..., this=0x7fffff800690) at
ex.h:305
#10 GiNaC::mul::expand (this=0x4096030, options=0) at mul.cpp:1490
#11 0x00007fff4ff9ac0d in GiNaC::ex::expand
(this=this@entry=0x7fffff800bf0, options=options@entry=0) at ex.cpp:84
#12 0x00007fff4ff9eec9 in expand (options=0, thisex=...) at ex.h:701
#13 GiNaC::match_monom (term=..., symb=..., vec=..., map=...) at
ex.cpp:523
#14 0x00007fff4ff9f8c8 in GiNaC::ex::coefficients
(this=this@entry=0x7fffff800e00, s=..., vec=...) at ex.cpp:576
#15 0x00007fff4ff9eed7 in GiNaC::match_monom (term=..., symb=...,
vec=..., map=...) at ex.cpp:523
#16 0x00007fff4ff9f8c8 in GiNaC::ex::coefficients
(this=this@entry=0x7fffff8011c0, s=..., vec=...) at ex.cpp:576
#17 0x00007fff4ff9eed7 in GiNaC::match_monom (term=..., symb=...,
vec=..., map=...) at ex.cpp:523
#18 0x00007fff4ff9f8c8 in GiNaC::ex::coefficients
(this=this@entry=0x7fffff801580, s=..., vec=...) at ex.cpp:576
#19 0x00007fff4ff9eed7 in GiNaC::match_monom (term=..., symb=...,
vec=..., map=...) at ex.cpp:523
#20 0x00007fff4ff9f8c8 in GiNaC::ex::coefficients
(this=this@entry=0x7fffff801940, s=..., vec=...) at ex.cpp:576
[...]
}}}

URL: https://trac.sagemath.org/23545
Reported by: vdelecroix
Ticket author(s): Ralf Stephan
Reviewer(s): Travis Scrimshaw

URL: https://trac.sagemath.org/24435
Reported by: embray
Ticket author(s): Erik Bray
Reviewer(s): Jeroen Demeyer

{{{
sage: SR(-oo) * SR(-oo)
-Infinity
}}}

URL: https://trac.sagemath.org/24327
Reported by: jdemeyer
Ticket author(s): Ralf Stephan
Reviewer(s): Travis Scrimshaw

Reported by bober on sage-nt, see
https://groups.google.com/forum/#!topic/sage-nt/AbtJF3Z5_fM.
{{{
sage: S = CuspForms(1728, 2)
sage: %time f = S.hecke_polynomial(2)
CPU times: user 17276.68 s, sys: 13.46 s, total: 17290.14 s
Wall time: 17293.59 s
sage: f
x^253 + x^251 - 2*x^249
}}}
Meanwhile, in a separate Sage session...
{{{
sage: %time M = ModularSymbols(1728, 2, 1)
CPU times: user 0.47 s, sys: 0.03 s, total: 0.50 s
Wall time: 0.54 s
sage: %time S = M.cuspidal_subspace()
CPU times: user 1.57 s, sys: 0.00 s, total: 1.57 s
Wall time: 1.54 s
sage: %time f = S.hecke_polynomial(2)
CPU times: user 19.09 s, sys: 0.00 s, total: 19.09 s
Wall time: 19.07 s
sage: f
x^253 + x^251 - 2*x^249
}}}

URL: https://trac.sagemath.org/21546
Reported by: kedlaya
Ticket author(s): David Loeffler
Reviewer(s): Vincent Delecroix

Use the next() built-in instead of next() method, and don't override the
next() built-in with a variable.

{{{
**********************************************************************
File "src/sage/rings/real_double.pyx", line 2790, in
sage.rings.real_double.time_alloc_list
Failed example:
    time_alloc_list(2)
Expected:
    [2.2, 2.1]
Got:
    [0.0, 1.0]
**********************************************************************
1 item had failures:
   1 of   4 in sage.rings.real_double.time_alloc_list
    [421 tests, 1 failure, 0.58 s]
----------------------------------------------------------------------
sage -t --long src/sage/rings/real_double.pyx  # 1 doctest failed
----------------------------------------------------------------------
}}}

URL: https://trac.sagemath.org/24358
Reported by: vbraun
Ticket author(s): Jeroen Demeyer
Reviewer(s): Volker Braun

A possible alternative to #24186, implementing simple conversion from C
`char` arrays or `bytes` objects to `str` objects, and of `str` objects
to `bytes` objects.  Here "`str`" and "`bytes`" are to be read exactly
for either Python 2 or Python 3, so on Python 2 this means no conversion
is performed since `str is bytes == True`.

One thing this does not do is implement any kind of conversion from
Python 2 `unicode` objects to `bytes`.  This functionality might be
worth adding, in some form, to `str_to_bytes`.  But this would add a
''new'' feature on Python 2, whereas for now I'm only trying to preserve
the existing functionality on Python 2 exactly, while transparently
supporting Python 3 `str`s everywhere that Python 2 `str`s are
supported.

URL: https://trac.sagemath.org/24222
Reported by: embray
Ticket author(s): Erik Bray, Jeroen Demeyer
Reviewer(s): Jeroen Demeyer, Erik Bray

URL: https://trac.sagemath.org/24402
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): Travis Scrimshaw

When numerically evaluating `complex_root_of(a, k)`, the index `k` is
passed as floating-point number:
{{{
sage: complex_root_of(x^8-1, 7).n(2)
------------------------------------------------------------------------
---
IndexError                                Traceback (most recent call
last)
<ipython-input-1-4eba84b7c14c> in <module>()
----> 1 complex_root_of(x**Integer(8)-Integer(1),
Integer(7)).n(Integer(2))

/home/patchbot/sage-patchbot/src/sage/structure/element.pyx in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)()
    863             0.666666666666667
    864         """
--> 865         return self.numerical_approx(prec, digits, algorithm)
    866
    867     N = deprecated_function_alias(13055, n)

/home/patchbot/sage-patchbot/src/sage/symbolic/expression.pyx in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36209)()
   5818         kwds = {'parent': R, 'algorithm': algorithm}
   5819         try:
-> 5820             x = x._convert(kwds)
   5821         except TypeError: # numerical approximation for real
number failed
   5822             pass          # try again with complex

/home/patchbot/sage-patchbot/src/sage/symbolic/expression.pyx in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)()
   1257         sig_on()
   1258         try:
-> 1259             res = self._gobj.evalf(0, kwds)
   1260         finally:
   1261             sig_off()

/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.pyc in _evalf_(self, poly, index, parent,
algorithm)
   2918         except AttributeError:
   2919             prec = 53
-> 2920         sobj = CRootOf(Poly(poly._sympy_()), int(index))
   2921         return sobj.n(ceil(prec*3/10))._sage_()
   2922

/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sympy/polys/rootoftools.pyc in __new__(cls, f, x, index,
radicals, expand)
    130         if index < -degree or index >= degree:
    131             raise IndexError("root index out of [%d, %d] range,
got %d" %
--> 132                              (-degree, degree - 1, index))
    133         elif index < 0:
    134             index += degree

IndexError: root index out of [-8, 7] range, got 8
}}}

When `gmpy2` is installed, the index is even passed as complex number:
{{{
sage -t --long src/sage/functions/other.py
**********************************************************************
File "src/sage/functions/other.py", line 2862, in
sage.functions.other.Function_crootof
Failed example:
    c.n()
Exception raised:
    Traceback (most recent call last):
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 517, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 920, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.functions.other.Function_crootof[1]>", line 1,
in <module>
        c.n()
      File "sage/structure/element.pyx", line 865, in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)
        return self.numerical_approx(prec, digits, algorithm)
      File "sage/symbolic/expression.pyx", line 5824, in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36286)
        x = x._convert(kwds)
      File "sage/symbolic/expression.pyx", line 1259, in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)
        res = self._gobj.evalf(0, kwds)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.py", line 2920, in _evalf_
        sobj = CRootOf(Poly(poly._sympy_()), int(index))
      File "sage/rings/complex_number.pyx", line 1058, in
sage.rings.complex_number.ComplexNumber.__int__
(build/cythonized/sage/rings/complex_number.c:10918)
        raise TypeError("can't convert complex to int; use int(abs(z))")
    TypeError: can't convert complex to int; use int(abs(z))
**********************************************************************
File "src/sage/functions/other.py", line 2864, in
sage.functions.other.Function_crootof
Failed example:
    c.n(100)
Exception raised:
    Traceback (most recent call last):
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 517, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 920, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.functions.other.Function_crootof[2]>", line 1,
in <module>
        c.n(Integer(100))
      File "sage/structure/element.pyx", line 865, in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)
        return self.numerical_approx(prec, digits, algorithm)
      File "sage/symbolic/expression.pyx", line 5824, in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36286)
        x = x._convert(kwds)
      File "sage/symbolic/expression.pyx", line 1259, in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)
        res = self._gobj.evalf(0, kwds)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.py", line 2920, in _evalf_
        sobj = CRootOf(Poly(poly._sympy_()), int(index))
      File "sage/rings/complex_number.pyx", line 1058, in
sage.rings.complex_number.ComplexNumber.__int__
(build/cythonized/sage/rings/complex_number.c:10918)
        raise TypeError("can't convert complex to int; use int(abs(z))")
    TypeError: can't convert complex to int; use int(abs(z))
**********************************************************************
File "src/sage/functions/other.py", line 2866, in
sage.functions.other.Function_crootof
Failed example:
    (c^6 + c + 1).n(100) < 1e-25
Exception raised:
    Traceback (most recent call last):
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 517, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 920, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.functions.other.Function_crootof[3]>", line 1,
in <module>
        (c**Integer(6) + c + Integer(1)).n(Integer(100)) <
RealNumber('1e-25')
      File "sage/structure/element.pyx", line 865, in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)
        return self.numerical_approx(prec, digits, algorithm)
      File "sage/symbolic/expression.pyx", line 5824, in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36286)
        x = x._convert(kwds)
      File "sage/symbolic/expression.pyx", line 1259, in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)
        res = self._gobj.evalf(0, kwds)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.py", line 2920, in _evalf_
        sobj = CRootOf(Poly(poly._sympy_()), int(index))
      File "sage/rings/complex_number.pyx", line 1058, in
sage.rings.complex_number.ComplexNumber.__int__
(build/cythonized/sage/rings/complex_number.c:10918)
        raise TypeError("can't convert complex to int; use int(abs(z))")
    TypeError: can't convert complex to int; use int(abs(z))
**********************************************************************
File "src/sage/functions/other.py", line 2908, in
sage.functions.other.Function_crootof._evalf_
Failed example:
    complex_root_of(x^2-2, 1).n()
Exception raised:
    Traceback (most recent call last):
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 517, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 920, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.functions.other.Function_crootof._evalf_[0]>",
line 1, in <module>
        complex_root_of(x**Integer(2)-Integer(2), Integer(1)).n()
      File "sage/structure/element.pyx", line 865, in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)
        return self.numerical_approx(prec, digits, algorithm)
      File "sage/symbolic/expression.pyx", line 5824, in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36286)
        x = x._convert(kwds)
      File "sage/symbolic/expression.pyx", line 1259, in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)
        res = self._gobj.evalf(0, kwds)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.py", line 2920, in _evalf_
        sobj = CRootOf(Poly(poly._sympy_()), int(index))
      File "sage/rings/complex_number.pyx", line 1058, in
sage.rings.complex_number.ComplexNumber.__int__
(build/cythonized/sage/rings/complex_number.c:10918)
        raise TypeError("can't convert complex to int; use int(abs(z))")
    TypeError: can't convert complex to int; use int(abs(z))
**********************************************************************
2 items had failures:
   3 of   5 in sage.functions.other.Function_crootof
   1 of   3 in sage.functions.other.Function_crootof._evalf_
    [622 tests, 4 failures, 17.27 s]
sage -t --long src/sage/interfaces/sympy.py
**********************************************************************
File "src/sage/interfaces/sympy.py", line 617, in
sage.interfaces.sympy._sympysage_crootof
Failed example:
    (sols[0]+1)._sage_().n()
Exception raised:
    Traceback (most recent call last):
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 517, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/doctest/forker.py", line 920, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.interfaces.sympy._sympysage_crootof[6]>", line
1, in <module>
        (sols[Integer(0)]+Integer(1))._sage_().n()
      File "sage/structure/element.pyx", line 865, in
sage.structure.element.Element.n
(build/cythonized/sage/structure/element.c:8131)
        return self.numerical_approx(prec, digits, algorithm)
      File "sage/symbolic/expression.pyx", line 5824, in
sage.symbolic.expression.Expression.numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:36286)
        x = x._convert(kwds)
      File "sage/symbolic/expression.pyx", line 1259, in
sage.symbolic.expression.Expression._convert
(build/cythonized/sage/symbolic/expression.cpp:10663)
        res = self._gobj.evalf(0, kwds)
      File "/home/patchbot/sage-patchbot/local/lib/python2.7/site-
packages/sage/functions/other.py", line 2920, in _evalf_
        sobj = CRootOf(Poly(poly._sympy_()), int(index))
      File "sage/rings/complex_number.pyx", line 1058, in
sage.rings.complex_number.ComplexNumber.__int__
(build/cythonized/sage/rings/complex_number.c:10918)
        raise TypeError("can't convert complex to int; use int(abs(z))")
    TypeError: can't convert complex to int; use int(abs(z))
**********************************************************************
1 item had failures:
   1 of   8 in sage.interfaces.sympy._sympysage_crootof
    [218 tests, 1 failure, 3.27 s]
}}}

URL: https://trac.sagemath.org/24378
Reported by: jdemeyer
Ticket author(s): Ralf Stephan
Reviewer(s): Jeroen Demeyer

The output of `one_solution` is random:
{{{
**********************************************************************
File "src/sage/combinat/matrices/dancing_links.pyx", line 27, in
sage.combinat.matrices.dancing_links
Failed example:
    sorted(x.one_solution(ncpus=8))
Expected:
    [0, 1]
Got:
    [2, 3]
**********************************************************************
1 item had failures:
   1 of  20 in sage.combinat.matrices.dancing_links
    [175 tests, 1 failure, 8.38 s]
----------------------------------------------------------------------
sage -t --long src/sage/combinat/matrices/dancing_links.pyx  # 1 doctest
failed
----------------------------------------------------------------------
}}}
Also, does ncpus=8 really use 8 cores? We already parallelize doctests!
Tests should definitely not x8 that.

URL: https://trac.sagemath.org/24424
Reported by: vbraun
Ticket author(s): Sébastien Labbé
Reviewer(s): Volker Braun

It is possible to specify a specific backend like `PolynomialRing(QQ,
'x', implementation="singular")` but the opposite (asking for a generic
Sage implementation) is not. Fix this by allowing
`implementation="generic"`.

This requires various fixes involving the `implementation` keyword being
ignored or breaking caching. In particular, we fix this caching bug:
{{{
sage: p = 2^64 + 13
sage: A = GF(p^2)
sage: B = GF(p^3)
sage: R = A.modulus().parent()
sage: S = B.modulus().parent()
sage: R is S
False
}}}

We also introduce a new implementation "GF2X" for the GF2X package. This
used be called "NTL" which we still allow as alias.

URL: https://trac.sagemath.org/24264
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): Travis Scrimshaw

The [[https://pypi.python.org/pypi/surface_dynamics/|surface_dynamics]]
package provides much more functionalities (and fixes) than what is
currently in Sage. This ticket proposes to deprecate all source code
from `sage.dynamics.flat_surfaces` and
`sage.dynamics.interval_exchanges` (with a message giving pointer to the
actual package).

URL: https://trac.sagemath.org/20695
Reported by: vdelecroix
Ticket author(s): Vincent Delecroix
Reviewer(s): Sébastien Labbé

A [https://www.openssl.org/news/secadv/20171207.txt security advisory]
appeared in openssl just after Sage 8.1 release. Since we are at the
beginning of the next release, let us take the opportunity to upgrade
from 1.0.2 to 1.1.0.

Tarball: https://www.openssl.org/source/openssl-1.1.0g.tar.gz

URL: https://trac.sagemath.org/24356
Reported by: tmonteil
Ticket author(s): Thierry Monteil
Reviewer(s): Volker Braun