add pretag and tag hooks.
pretag hook lets hook decide how tags can be named. tag hook is
notifier.
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
changeset: 0:acb14030fe0a
tag: tip
user: test
date: Thu Jan 1 00:00:00 1970 +0000
summary: test
rolling back last transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
0 files, 0 changesets, 0 total revisions
A a