use source version of surface dynamics

1 job for travis in 11 minutes and 7 seconds (queued for 1 minute and 11 seconds)
latest
Status Job ID Name Coverage
  Test
failed #209418410
python2.7

00:11:07

 
Name Stage Failure
failed
python2.7 Test
       ^~~~~~~~~~~~~~~~
surface_dynamics/interval_exchanges/integer_iet.c:6775:3: warning: statement with no effect [-Wunused-value]
print_backtrace;
^~~~~~~~~~~~~~~
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-uDzYev-build/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-Uhgf96-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-uDzYev-build/
ERROR: Job failed: exit code 1