A post checkout hook to automatically remove *.pyc files.

post-checkout

#! /bin/sh
green='\033[0;32m'
nc='\033[0m'

# Start from the repository root.
cd ./$(git rev-parse --show-cdup)

# Delete .pyc files and empty directories.
echo "${green}Deleting PYC files...${nc}"
find . -name "*.pyc" -delete
find . -type d -empty -delete

echo "${green}Resetting submodules...${nc}"
git submodule foreach git reset --hard HEAD
git submodule update

Save to .git/hooks/post-commit and make executable chmod +x .git/hooks/post-commit.

http://stackoverflow.com/questions/1504724/a-git-hook-for-whenever-i-change-branches#answer-1810193

In your comment above, do you mean "post-commit"? Or maybe "post-checkout"?