Git Hook: Example post-merge hook that checks for updates to requirements.txt

post-merge

#!/usr/bin/env python
import sys
import subprocess

diff_requirements = 'git diff ORIG_HEAD HEAD --exit-code -- requirements.txt'

exit_code = subprocess.call(diff_requirements.split())
if exit_code == 1:
    print 'The requirements file has changed! Remember to install new dependencies.'
else:
    print 'No new dependencies.'

To use this hook:
Copy it to .git/hooks/post-merge
Ensure it's executable with chmod +x .git/hooks/post-merge