[Meta] Support "main" as a default branch name

[TimidRobot]

Description

This ticket tracks the variety of changes required to support main as a default branch name for the creativecommons and cc-archive GitHub organizations.

Rationale

Master-slave is an oppressive metaphor that will and should never become fully detached from history. Aside from being unprofessional and oppressive it stifles participation

(1.1. Master-slave - Terminology, Power and Oppressive Language)

While not everyone may interpret a git master branch as representing a "master-slave" metaphor, it is not unreasonable for anyone to do so:

First appearance of "master" in git is in a CVS helper script[1]:
git/git@3e91311

Why is that branch called master? Probably because BitKeeper uses
"master" for its main branch:
http://www.bitkeeper.org/tips.html#_how_do_i_rebase_my_work_on_top_of_a_different_changeset

But maybe this "master" isn't the same one that's in "master/slave"?
See the documentation about
master/slave repositories:
https://github.com/bitkeeper-scm/bitkeeper/blob/master/doc/HOWTO.ask#L223

But repositories and branches aren't the same! They are in BitKeeper:
https://users.bitkeeper.org/t/branching-with-bk/158/2

So, yes, the "git master" branch probably isn't even a "master copy"
reference, but a straight up master/slave reference.

(Re: Replacing "master" reference in git branch names (was Re: Proposal:)

Continuing to use master as a default branch name is unwelcoming of too many. We should put our best face forward, not a face that others can easily interpret as hostility or white supremacy.

Implementation Details

1. Identify and resolve issues that prevent main from being used a default branch name and track them, below.
2. Project maintainers will decide per repository whether they want to move to using main and track them, below.
3. The Creative Commons Engineering team will re-evaluate based on the experience of using main in those repositories within ~6 months (2020 end of November or beginning of December)

Prerequisites

• Also support "main" as default branch for repo normalization · Issue #48 · creativecommons/ccos-scripts
• Update Pull Request template to support "main" as a default branch name · Issue #10 · creativecommons/.github
• Support for renaming an existing branch - GitHub Changelog (2021-01-19)
  • github/renaming: Guidance for changing the default branch name for GitHub repositories

Additional context

• Easily rename your Git default branch from master to main - Scott Hanselman
• Terminology, Power and Oppressive Language
• Additional proof that it has been a "master-slave" metaphor since the beginning:
  • 'Re: kernel.org and GIT tree rebuilding' - MARC (2005 email from Linus Torvalds to git mailing list)

[TimidRobot]

Related

• GitHub to replace "master" with alternative term to avoid slavery references | ZDNet