echo 4 >d && git add d &&
test_tick && git commit -S -m "bad" &&
git cat-file commit HEAD >raw &&
- sed -e "s/bad/forged bad/" raw >forged &&
+ sed -e "s/^bad/forged bad/" raw >forged &&
git hash-object -w -t commit forged >forged.commit &&
git checkout $(cat forged.commit)
) &&