Pull request commit links have been recently broken

These commit links have been recently broken on GitHub.com:

They link to https://github.com/<commit_author>/<repo_name>/pull/<id>/commits/<sha>. That link 404s because the pull request ID does not exist on <commit_author>/<repo>, redirecting to https://github.com/<commit_author>/<repo>/issues/<id>.

The correct link should be https://github.com/<THE_AUTHOR_OF_THIS_UPSTREAM_REPO>/<repo_name>/pull/<id>/commits/<sha> instead.

This was also reported in Bug: Clicking on PR commit links causes 404 (about one hour earlier).