Old versions of git lack --force and --tags,
but the same effect can be had by specifying refspecs.

The test assumes that a directory with write permission removed isn't writable,
this isn't the case if the process running the tests has CAP_DAC_OVERRIDE
which is common when running as root.

test_track_invalid_submodule depends on being able to remove a submodule
by `git rm $submoduledir`, but old versions of git don't update .gitmodules
so BuildStream still thinks there's a submodule present.

For expediency the test is skipped rather than changed to manually remove
the entry from .gitmodules if git hasn't done it,
since in the common case git is new enough to do that itself.

test_git_describe expects --first-parent to find another tag,
but `bst track` will gracefully degrade if the option doesn't work
so a different history will be retained with old versions of git.

It's of marginal benefit to add additional cruft
to test for different output on old versions of git that won't persist forever.

Benjamin Schubert authored Dec 20, 2018 and richardmaw-codethink committed Jan 21, 2019

Centos is apparently different enough from fedora when running tests.

Fix CentOS

Closes #833

See merge request !1085

The link explaining python's requirements files was formatted
incorrectly (missing underscore at the end). This resulted in the text
being rendered literally, as opposed to being converted into a
hyperlink.

CONTRIBUTING.rst: Fix formatting of link to pip docs

See merge request !1094

There is no reason to disallow guess_element() for bst build --all.

_frontend/cli.py: Use new methods.

Based on patches by Phillip Smyth.

This filters out junctions from the list of targets.

Junctions cannot be built, pulled, or pushed. Specifying a junction on
the command line for these commands will result in an error. However,
junctions may be in the list of default targets, so they need to be
ignored for build, pull, and push commands.

Test that `bst build` does not fail in a project where the list of
default targets includes a junction (junctions cannot be built).