This makes iotest 033 pass with e.g. subformat=monolithicFlat.  It also
turns a former error in 059 into success.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190815153638.4600-3-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>