This new test verifies that VMDK backing file reads fail when the
backing file has a non-matching CID.  This includes non-VMDK backing
files.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20180702210721.4847-3-mreitz@redhat.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>