A script to help merge multiple branches based off each other. For dealing with slow reviews but still trying to make small behavior or structural change PRs.

git-merge-train

#!/bin/bash

: ${DRY_RUN:=true}

if [ $# -lt 2 ]; then
    echo "Usage: git merge-train <first branch> <branch based on first branch> [... branches based on previous]"
    exit 0
fi

if [ "${DRY_RUN}" != 'false' ]; then
    echo "In dry run mode. To rebase the entire merge train run:"
    echo "    DRY_RUN=false git merge-train $@"
fi

branch_before=$(git branch --show-current)
parent_branch=master
for branch in ${@}; do
    echo git merge-base --fork-point $parent_branch $branch
    fork_point=$(git merge-base --fork-point $parent_branch $branch)
    if [ $? -ne 0 ]; then
        echo "getting merge base failed, aborting: ${fork_point}" >&2
	exit 1
    fi

    git checkout ${branch}
    if [ "${DRY_RUN}" != 'false' ]; then
        echo "git rebase --onto ${parent_branch} ${fork_point}"
    else
        git rebase --onto ${parent_branch} ${fork_point}
    fi

    parent_branch=$branch
done
git checkout ${branch_before}