test-kpartx: add test for invocation on image file
Add a test for kpartx invocation on an image file that is not
yet part of a loop device, passing a relative path to kpartx:
# kpartx -av disk.img
...
# kpartx -d disk.img
The recent patches
95c4189b "kpartx: Use absolute paths to create mappings"
and
c1adcc5b "kpartx: Use absolute paths to create mappings" both
independently fixed this behavior, which had been broken previously by
9bdfa3eb "kpartx: use absolute path for regular files".
Cc: Stef Walter <stefw@redhat.com>
Cc: Yuval Turgeman <yturgema@redhat.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>