Merges a repo into a subdirectory of another repo (useful when making a submodule part of a parent repo)

merge-repo-to-subdir.sh

#!/bin/bash -e

function merge_repo_to_subdir {
	local url=$1
	local commit=$2
	local module_path=$3
	if [[ -z $url || -z $commit || -z $module_path ]]; then
		echo "Usage: merge-repo-to-subdir.sh URL BRANCH PATH" >&2
		exit 1
	fi
	local remote_name
	local branch_name
	remote_name=$(basename "$url")
	branch_name=$(basename "$url")

	git remote add -f "$remote_name" "$url"
	git branch "$branch_name" "$commit"

	git filter-branch -f --index-filter \
		'git ls-files -s | gsed "s-\t\"*-&'${module_path//-/\\-}'/-" |
GIT_INDEX_FILE=$GIT_INDEX_FILE.new \
git update-index --index-info && \
mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE" \
|| test ! -e "$GIT_INDEX_FILE.new"' "$branch_name"

	git merge --allow-unrelated-histories "$branch_name"
	git branch -D "$branch_name"
	git remote rm "$remote_name"
	git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d
	git reflog expire --verbose --expire=0 --all
	git gc --prune=0
}

merge_repo_to_subdir "$1" "$2" "$3"