Merge pull request opencv#14443 from dkurt:fix_14435

Author: alalek

modules/dnn/misc/python/test/test_dnn.py

@@ -209,8 +209,10 @@ def test_async(self):
                 outs.insert(0, netAsync.forwardAsync())
 
             for i in reversed(range(numInputs)):
-                if outs[i].wait_for(timeout) == 1:
+                ret = outs[i].wait_for(timeout)
+                if ret == 1:
                     self.fail("Timeout")
+                self.assertEqual(ret, 0)  # is ready
                 normAssert(self, refs[i], outs[i].get(), 'Index: %d' % i, 1e-10)