gistfile1.sh

$ cat .git/hooks/post-checkout
#!/bin/bash

# Remove stray .pyc files
find . -name '*.pyc' -delete

# Update requirements if needed
for filename in requirements.txt dev-requirements.txt test-requirements.txt ; do
    CHANGED=`git diff HEAD@{1} --stat -- $GIT_DIR/../$filename | wc -l`
    if [ $CHANGED -gt 0 ];
    then
        echo "$filename has changed!"
        pip install -r $filename
    fi
done