[Bugfix] Don't unset global git user config after git tests

[Syphdias]

Currently running the git unit tests unsets name and email in the global git config.

This PR gets rid of unnecessary variable juggling and simply sets the git config in the new home. The config (/tmp/powerlevel9k-test/.gitconfig) will be removed when the test directory is removed. I also added a "test" (which is a bit of a hack) to check if email or name were changed.

PS: Teardowns are currently called an additional time (see kward/shunit2#112 for details) after shunit finished all tests. It should be fine for now. Just a heads up since I stumbled upon this bug while testing.

[dritter]

Overall I like the Idea of cleaning that up, but I have a bit different implementation in mind. This fiddling around with the git config was done, because we didn't had a better way to set a temporary configuration for the test. Later on, somebody else did just redeclare the HOME directory for a test. I think we could do the same here: Just set $HOME to a temporary directory, and write a ~/.gitconfig there. That should work as well, and we won't have to figure out the original git settings at first and reset them afterwards..

[Syphdias]

@dritter I'm confused. How is that not what is being done here? Which is why I deleted most of the setting resets.

I also added the test to ensure the user config modification doesn't happen again. This apparently failed on Mac OS...

[dritter]

Ha! I missed that line (folded away by github).

So I adjust my comment: I wouldn't trust git config --global, and instead just write the config file directly to our newly created HOME folder.. ;)

[dritter]

Thanks @Syphdias .