When an object is deleted, we retrieve its metadata on the next PUT
requests, which make if-none-match requests fail while the object
shouldn't be here. It seems we're only interested in the timestamp of
the deleted object, so get that but forget the metadata.
Change-Id: I4a4a8be9b631598ca1cd52c53885c68c3fbdfc4a
Closes-Bug: #1640448