#!/bin/bash

# Get the commit hashes to keep:
#  We want the newest commit (which removed all unwanted cruft)
#  We want all commits that show up in a git blame on any existing file
commit_hashes=$(git rev-parse HEAD)" "$(git ls-files | xargs -I{} git blame --minimal --abbrev=40 -- {}|grep -vF '^'| awk '{print $1}' | sort -u)
                                                                                                                        
                                                                                                                        
# Rewrite the Git history to remove obsolete commits
if [ "$commit_hashes" != "" ]; then
    git filter-branch --commit-filter '
        if echo "'"$commit_hashes"'" | grep -q "$GIT_COMMIT"; then
            git commit-tree "$@";
        else
            skip_commit "$@";
        fi' HEAD
fi