Although SPC-2 specifies that a reservation conflict should be
reported when TEST UNIT READY is received from another initiator than
the registered initiator, it is an established practice that TEST
UNIT READY is accepted in this case. Hence use the MODE SENSE command
to test the effect of the RESERVE command instead of TEST UNIT READY.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>