Get the list of PEP8 errors you have introduced. Ignores "E501 Line too long" and "W293 Whitespace in empty line". This be changed from IGNORED_RULES value. Checkout the repository you want to check and call `pep8_introduced.sh master` (replace master with the target branch)

pep8_introduced

#!/bin/bash

CURRENT_BRANCH=`git branch --no-color | grep '*' | sed s/\*\ //`
TARGET_BRANCH=$1
CHANGED_FILE_LIST=filelist.diff.tmp
TARGET_PEP8="$TARGET_BRANCH".pep8.tmp
CURRENT_PEP8="$CURRENT_BRANCH".pep8.tmp
IGNORED_RULES="E501,W293"

if [[ -z "$1" ]]; then
	echo 'Usage: ./pep_introduced.sh target_branch'
	echo
else
	exec 7<&2
	exec 2<&-
	git checkout $TARGET_BRANCH
	git diff --name-only "$TARGET_BRANCH".."$CURRENT_BRANCH" | grep .py > $CHANGED_FILE_LIST

	echo > $TARGET_PEP8
	echo > $CURRENT_PEP8

	while read line
	do
		pep8 --ignore $IGNORED_RULES $line >> $TARGET_PEP8
	done < $CHANGED_FILE_LIST


	git checkout $CURRENT_BRANCH 
	while read line
	do
		pep8 --ignore $IGNORED_RULES $line >> $CURRENT_PEP8
	done < $CHANGED_FILE_LIST

	exec 2<&7
	exec 7<&-
	diff $TARGET_PEP8 $CURRENT_PEP8 | grep '^>' | sed s/^\>\ //
	rm $TARGET_PEP8
	rm $CURRENT_PEP8
	rm $CHANGED_FILE_LIST
fi