Old branch/tag naming standards hooks don't respond to UI-based triggers

Responsibility for enforcing branch naming standards used to be shared between a pre-hook (for e.g. pushes) and an event handler (for UI creations/renamings). With the introduction of the new Hooks API, the pre-hook took on full responsibility and the event handler became a no-op, but only newly-created pre-hooks would respond to all the necessary triggers - pre-existing hooks have not been retroactively amended.