I edited MediaWiki:AnonymousI18N.js on Commons, which is loaded from MediaWiki:Common.js using the canonical, long-cached, supposed-to-be-purged URL:
However, neither on edit, nor on the dozens of purge attempts later, it's not getting purged from the CDN.
Looking into the code, where this is supposed to be, I see that there is a pretty obvious bug: It checks for isUserJsConfigPage() which is limited to NS_USER. This code is now in HtmlCacheUpdater service class, but used to be in Title::getCdnUrls.
The code was changed in change 410085, which removed the confusingly-ambigiously named isJsSubpage() method to isUserJsConfigPage(), based on the inline comment which gave this further false confidence that it wasn't a bug, when in fact it was:
// If we are looking at a css/js user subpage, purge the action=raw if ( $this->isJsSubpage() ) {