iotests: Do not needlessly filter _make_test_img
In most cases, _make_test_img does not need a _filter_imgfmt on top. It
does that by itself.
(The exception is when IMGFMT has been overwritten but TEST_IMG has not.
In such cases, we do need a _filter_imgfmt on top to filter the test's
original IMGFMT from TEST_IMG.)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <
20201027190600.192171-8-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>