Make "hg incoming -r revision_number" work for remote repos (
issue566)
Uses the remote repository's lookup method as pull does and only transfers
what is needed to calculate incoming changesets.
One minor problem:
As only the needed changesets are transfered and stored in a local bundle
repository, the tip tag of this bundle is shows despite not being the tip
changeset of the remote repository.
(see "+tag: tip" in tests/test-incoming-outgoing.out in this patch)