Given branch/ref (e.g. my_branch) and target (e.g. origin/master), lists commits in branch that have no "equivalent" ones in target (by author, date and message)

git-unmerged-commits

#!/bin/bash
set -eu

# Similar to git branch --merged but looks at commit author, date and
# subject, instead of hash.
#
# Given branch/ref (e.g. my_branch) and target (e.g. origin/master),
# lists commits in branch that have no "equivalent" ones in target (by
# author, date and message).

# Example usage:
#
#   git unmerged-commits origin/master my_branch -- my_path
#
# You can use it to (very slowly) list all branches that are merged 
# (even after being rebased, so that commit hashes don't matter):
#
#   git branch | grep -vF '*' | xargs -n1  -iBRANCH bash -c 'git unmerged-commits origin/master BRANCH >/dev/null || echo BRANCH'
#

TARGET="$1" # e.g. origin/master
shift
BRANCH="$1" # e.g. my_branch
shift
EXTRA_ARGS_TO_GIT_LOG="$@"

MERGE_BASE=$(git merge-base $TARGET $BRANCH)

list_commits() {
    HEAD="$1"
    shift
    EXTRA_ARGS="$@"
    git log $MERGE_BASE..$HEAD --format="%an %ai %s" $EXTRA_ARGS
}

TARGET_COMMITS_FILE="$(mktemp)"

cleanup() {
    test -f "$TARGET_COMMITS_FILE" && rm "$TARGET_COMMITS_FILE"
}

trap "cleanup" EXIT

list_commits $TARGET $EXTRA_ARGS_TO_GIT_LOG > $TARGET_COMMITS_FILE

list_commits $BRANCH $EXTRA_ARGS_TO_GIT_LOG | grep -vxFf $TARGET_COMMITS_FILE