Merge branch 'ps/the-index-is-no-more' into ps/undecided-is-not-necessarily-sha1

* ps/the-index-is-no-more: repository: drop `initialize_the_repository()` repository: drop `the_index` variable builtin/clone: stop using `the_index` repository: initialize index in `repo_init()` builtin: stop using `the_index` t/helper: stop using `the_index`