Fixing doc building with newer pip versions

[xentec]

CalledProcessError should only be raised, if 'No command ...' is in stderr, not otherwise.

[xentec]

Well, this is interesting: Travis somehow fails on the opposite, indicating that his pip version does not support show.

Is the check for show support even necessary?

[vitaut]

Thanks for the PR, but the logic looks correct (although the comment could be better). pip show is used to check if the package is already installed. If the show command is not supported pip gives error "No command by the name pip show" which is ignored and the installation continues, otherwise a CalledProcessError exception is thrown.

Is the check for show support even necessary?

Yes, the check is necessary because the old version of pip installed on travis doesn't support the show command.

Is there any problem when you run unchanged build.py?

[xentec]

Yes, I get the CalledProcessError when building it on Arch Linux, because p.returnCode is 1 but stderr (and stdout) is empty.
Using virtualenv 13.1.0 and pip 7.1.0.

[vitaut]

Could be a change in pip behavior. What happens when you run pip show somenoninstalledpackage from a command line, does it return nonzero error code and doesn't print anything?

[xentec]

Pretty much.

» doc/virtualenv/bin/pip show breathe; echo $?
1
» doc/virtualenv/bin/pip show somenoninstalledpackage; echo $?
1
» doc/virtualenv/bin/pip show sphinx; echo $?
---
Metadata-Version: 2.0
Name: Sphinx
Version: 1.3.1
Summary: Python documentation generator
Home-page: http://sphinx-doc.org/
Author: Georg Brandl
Author-email: georg@python.org
License: BSD
Location: /home/xentec/build/cppformat-git/src/cppformat-git/build/doc/virtualenv/lib/python3.4/site-packages
Requires: Jinja2, alabaster, babel, Pygments, six, sphinx-rtd-theme, snowballstemmer, docutils
0

[vitaut]

I've tried to modify the logic in build.py to make it work with the new version of pip: 3b224e1

Does it work for you?

[xentec]

I updated my fix, which is not pretty nor very future proof.
Let's just hope this won't need as much tinkering as you needed with MinGW.

[vitaut]

Merged, thanks!

One way to improve this is to ignore the error from pip show altogether but the current approach is OK too even if it is not particularly pretty.

Let's just hope this won't need as much tinkering as you needed with MinGW.

Haha yeah, MinGW32 was a bit of pain.