If you have a branch name with .py in it, compileall will fail with bad syntax

This was one of the fun ones to track down:
```
SyntaxError: ('invalid syntax', ('/edx/app/edxapp/edx-platform/.git/refs/remotes/origin/oliviermarquez/update-tabs.py', 1, 40, '925133409b1d81997e04e9c6d9ff58f01e309f46\n'))
```
Turns out python will try and compile everything, even git branches, and it isn't so good at git branches.