Windows: Python error on "fips diag fips" if Git not in path

[code-disaster]

Only a minor annoyance, but I don't have Git added to the system path on my Windows system. This is easily avoidable by using Git Bash instead of cmd.exe, but maybe you want to add a check for this.

=== tools:
git: NOT FOUND (git not found in path, can't happen(?))

=== fips:
[...]
File "D:\projects\noise-fips/fips\mod\tools\git.py", line 50, in get_branches
output = subprocess.check_output(['git', 'branch', '-vv'], cwd=proj_dir)
File "C:\Python27\lib\subprocess.py", line 566, in check_output
process = Popen(stdout=PIPE, _popenargs, *_kwargs)
[...]
WindowsError: [Error 2] Das System kann die angegebene Datei nicht finden

[floooh]

Thanks! I have added a check around git operations, but only tested on OSX so far.