fetch: describe new refs based on where it came from

fetch: describe new refs based on where it came from

update_local_ref() used to say "[new branch]" when we stored a new ref
outside refs/tags/ hierarchy, but the message is more about what we
fetched, so use the refname at the origin to make that decision.

Also, only call a new ref a "branch" if it's under refs/heads/.

Signed-off-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>