Fixed tests execution with Python 2.7

modules/python/src2/cv2_util.hpp

@@ -71,7 +71,7 @@ public:
     }
 
     operator bool() {
-        return static_cast<bool>(obj_);
+        return obj_ != nullptr;
     }
 
     PyObject* release()

modules/python/test/test_misc.py

@@ -223,9 +223,14 @@ class Arguments(NewOpenCVTests):
         for dtype in (object, str, np.complex128):
             test_array = np.zeros((4, 4, 3), dtype=dtype)
             msg = ".*type = {} is not supported".format(test_array.dtype)
-            self.assertRaisesRegex(
+            if sys.version_info[0] < 3:
-                Exception, msg, cv.utils.dumpInputArray, test_array
+                self.assertRaisesRegexp(
-            )
+                    Exception, msg, cv.utils.dumpInputArray, test_array
+                )
+            else:
+                self.assertRaisesRegex(
+                    Exception, msg, cv.utils.dumpInputArray, test_array
+                )
 
     def test_20968(self):
         pixel = np.uint8([[[40, 50, 200]]])