Run flake8 on the set of changes in a pre-commit hook

flake8-pre-commit

#!/bin/bash
# Place in .git/hooks/pre-commit
# Filters out deleted files with --diff-filter

# GNU
git diff --cached --name-only  --diff-filter=ACMRTUXB | grep .py | xargs --no-run-if-empty flake8 $FLAKE

# BSD
git diff --cached --name-only  --diff-filter=ACMRTUXB | (grep .py || echo " ") | xargs flake8 $FLAKE

To ignore all errors when committing:

FLAKE="--exit-zero" git commit <files>