This tests that when an error happens while writing back bitmaps to the
image file in qcow2_inactivate(), 'qemu-img bitmap/commit' actually
return an error value in their exit code instead of making the operation
look successful to scripts.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230112191454.169353-5-kwolf@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>