Ensure that when an item fetched from a premirror has an invalid checksum the
fetcher falls back to the usual logic of trying the upstream and any configured
mirrors.
(Bitbake rev: 022adb30dbb0df764c9fb515918cb9a88e4f8d6f)
Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>