C Git always fetches tags during clone, even if the tag doesn't
point to an object that was fetched by the branch specifications.
Match that behavior, as users expect it.
Bug: 326611
Change-Id: I81a82b7359a9649f18a172219da44ed54e77ca2f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>