Misc #15843

Updated by k0kubun (Takashi Kokubun) 6 months ago

## Background

* We're using `trunk` branch as a canonical development branch because it has been mirrored to there by git-svn.
* In a usual git repository, a HEAD branch is `master` by default. Using `trunk` instead of `master` is confusing and causes typo on git operations or typing git-related URLs.
* We can make an *alias branch* by using symbolic-ref on ``. We can start using `master` branch without disturbing any `trunk` usage. Why not use it?

## Proposed schedule

* 2019
* 5/22: Announce this schedule
* 5/23: Make `master` symbolic-ref pointing to `trunk` on
* 5/23~6/30: Ask maintainers of CI (or whatever integrated with the repository) to explicitly use `master` branch instead of `trunk` at ruby-core mailing list.
* 7/1: Switch HEAD on from `trunk` to `master` (change the default branch of GitHub ruby/ruby to `master` too)
* 2020
* 1/1: Drop `trunk` branch on (`mv refs/heads/trunk refs/heads/master` at `/var/git/ruby.git`)