Fix Python 2 compat

src/greentest/test__greenlet.py

@@ -700,11 +700,10 @@ class TestBasic(greentest.TestCase):
             gevent.sleep(0.01)
 
     def test_add_spawn_callback(self):
-        called = 0
+        called = {'#': 0}
 
         def cb(gr):
-            nonlocal called
-            called += 1
+            called['#'] += 1
             gr._called_test = True
 
         gevent.Greenlet.add_spawn_callback(cb)
@@ -712,24 +711,24 @@ class TestBasic(greentest.TestCase):
             g = gevent.spawn(lambda: None)
             self.assertTrue(hasattr(g, '_called_test'))
             g.join()
-            self.assertEqual(called, 1)
+            self.assertEqual(called['#'], 1)
 
             g = gevent.spawn_later(1e-5, lambda: None)
             self.assertTrue(hasattr(g, '_called_test'))
             g.join()
-            self.assertEqual(called, 2)
+            self.assertEqual(called['#'], 2)
 
             g = gevent.Greenlet(lambda: None)
             g.start()
             self.assertTrue(hasattr(g, '_called_test'))
             g.join()
-            self.assertEqual(called, 3)
+            self.assertEqual(called['#'], 3)
 
             gevent.Greenlet.remove_spawn_callback(cb)
             g = gevent.spawn(lambda: None)
             self.assertFalse(hasattr(g, '_called_test'))
             g.join()
-            self.assertEqual(called, 3)
+            self.assertEqual(called['#'], 3)
         finally:
             gevent.Greenlet.remove_spawn_callback(cb)