For example, OOjs UI is a versioned library bundled in MediaWiki core. Right now, @Jdforrester-WMF adds OOjs-UI-next-release to each task as the code is merged. When the release is made, this is converted to OOUI (OOjs-UI-0.11.0) etc. Finally, when the new version of the library is pulled-through to MediaWiki, it's additionally tagged with the MediaWiki release branch so people know when it will hit production.
(This workflow is very complicated and right now only applies to one project, so not necessarily a real blocker.)