[MERGE] Reduce overhead on commit by using knit specific API

[Martin Pool]

Martin Pool has voted approve.
Status is now: Approved
Comment:

          self._check_ascii_revisionid(revision_id, 
self.get_commit_builder)
-        return Repository.get_commit_builder(self, branch, parents, 
config,
-            timestamp, timezone, committer, revprops, revision_id)
+        revision_id = osutils.safe_revision_id(revision_id)

safe_revision_id is a bit redundant with _check_ascii_revisionid, but 
since
this is old code I think it's harmless to have both.

please merge it now for 0.91


For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C1189376274.20312.10.camel%40lifeless-64%3E