A small, inefficient, naïvely-written bash script to list all duplicate commits (those with the same patch-id) in a git repo.

git-list-dupe-commits

#!/usr/bin/env bash

test ! -z "$1" && TARGET_COMMIT_SHA="$1" || TARGET_COMMIT_SHA="HEAD"

TARGET_COMMIT_PATCHID=$(
git show --patch-with-raw "$TARGET_COMMIT_SHA" |
	git patch-id |
	cut -d' ' -f1
)
MATCHING_COMMIT_SHAS=$(
for c in $(git rev-list --all); do
	git show --patch-with-raw "$c" |
		git patch-id
done |
	fgrep "$TARGET_COMMIT_PATCHID" |
	cut -d' ' -f2
)

echo "$MATCHING_COMMIT_SHAS"