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: cc52b9b12c60810142252b9cb5d4268e42371b8e)
Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>