Improve pruning of branches in outstanding changeset algorithm These changes make the client keep track of what it's seen more carefully to avoid some redundant requests.

A new ancestor algorithm The old ancestor algorithm could get fooled into returning ancestors closer to root than it ought to. Hopefully this one, which strictly orders its search by distance from room, will be foolproof.

Handle merge with deletions If you merge with a repo that has deleted a file after editing it, hg attempted to resolve the file. This (correctly) resulted in hg verify errors because the resolved version didn't show up in the manifests. This moves the manifest resolution before file resolution and decides which files to resolve based on the (partially) resolved manifest. After files are resolved, the final manifest is committed.

Minor fixes to verify