zdtm.py: Print more info when maps compare fails

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.py

@@ -607,6 +607,14 @@ def check_visible_state(test, state):
 	if cmp_lists(new[0], state[0]):
 		raise test_fail_exc("fds compare")
 	if cmp_lists(new[1], state[1]):
+		s_new = set(new[1])
+		s_old = set(state[1])
+
+		print "Old maps lost:"
+		print s_old - s_new
+		print "New maps appeared:"
+		print s_new - s_old
+
 		raise test_fail_exc("maps compare")
 
 def do_run_test(tname, tdesc, flavs, opts):