Now I'm not saying we shouldn't be getting rid of branches we don't need anymore...

But when you look at older (a few weeks?) Wikimedia-production-error bugs, and try and click on the URLs in the stacktrace (for example T380880), you end up with links such as https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/core/+/refs/heads/wmf/1.44.0-wmf.4/includes/ExternalLinks/LinkFilter.php#278 which results in an error of "Cannot parse URL as a Gitiles URL"