I've experienced this before. Not that .pyc/.pyo files ever get into my repo, but sometimes Python will decide it doesn't need to recompile the files and I get old behavior from a piece of software I know I've just re-deployed.

My solution? Simple, I've got a a Fabric command that deletes all .pyc files in the repo after pulling.

def clean_pyc(): run('find . -name "*.pyc" -exec rm {} \;')

And that's that :)