repository: introduce register_changeset callback The new callback is called whenever a changeset is added to the repository (commit, unbundle or exchange). Since the bulk operations already parse the changeset (readfiles or full changesetrevision), always use the latter to avoid redundant lookups. The first consumer of the new interface needs to look at extra. Differential Revision: https://phab.mercurial-scm.org/D9780

changelog: move branchinfo to changelogrevision The function parses the extra dictionary after looking up the changelogrevision. To avoid duplicated look up, it is better to provide it as property of changelogrevision instead. Keep the function for a release cycle as at least the topic extension depends on it. Differential Revision: https://phab.mercurial-scm.org/D9779