MultiRepos: Refactored the `trac-post-commit-hook` into a sample plugin `commit_ticket_update.py` using `IRepositoryChangeListener`.
* Added an `old_changeset` argument to the `changeset_modified()` hook, providing the old changeset metadata if available (or `None` otherwise).
Part of #7723, closes #5189.
Authored by: rblank 2009-04-10
Parent: [r8093]
Child: [r8095]