Test 052 uses qemu-io -s which will result in bdrv_open trying to create
a temporary snapshot file in /tmp. However, since O_DIRECT and tmpfs
do not work well together, disable this test for -nocache.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>