t: restui: fix unpairing assertion
t: restui: fix unpairing assertion

As unpairing operation may not be performed immediately, we may need
the last check that tells whether the unpairing failed or succeed.

Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server