wporg-markdown importer - Support GitHub branches not named `master`

[netweb]

Currently the get_markdown_edit_link() function hard codes the GitHub edit link to master: (​Source)

		if ( 'github.com' !== parse_url( $markdown_source, PHP_URL_HOST )
			|| false !== stripos( $markdown_source, '/edit/master/' ) ) {
			return $markdown_source;
		}
		$markdown_source = str_replace( '/blob/master/', '/edit/master/', $markdown_source );

Discovered after merging ​https://github.com/WordPress/WordPress-Documentation-Style-Guide/pull/20 where the default branch is main, prior to merging the above PR the GitHub "edit" URL on pages were in the form:

• https://github.com/WordPress/WordPress-Documentation-Style-Guide/edit/master/docs/2-general-guidelines/6-facts-claims.md
  • (Via the ​https://make.wordpress.org/docs/style-guide/general-guidelines/facts-claims/ page)

The above URL format 404s as the master branch no longer exists on GitHub

The new "edit" URL on pages is:

• https://github.com/WordPress/WordPress-Documentation-Style-Guide/main/docs/2-general-guidelines/6-facts-claims.md
  • (Via the ​https://make.wordpress.org/docs/style-guide/general-guidelines/facts-claims/ page)

And as such the URL doesn't include /edit/main, just /main, so the URL opens correctly just not in the previous "edit" mode.

My suggestion would be to update the above function to account for common dotorg repo branch names used: trunk, main, and master

[dd32]

In 12118:

Markdown Importer: Support any branch in the imported content, not just master.

Fixes #6538.