diff -r 37905786b34b Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Sun Apr 12 23:24:17 2015 -0500
+++ b/Lib/unittest/mock.py	Mon Apr 13 17:21:47 2015 +0200
@@ -1789,14 +1789,15 @@
 
 class MagicMixin(object):
     def __init__(self, *args, **kw):
+        self._mock_set_magics()  # make magic work for kwargs in init
         _safe_super(MagicMixin, self).__init__(*args, **kw)
-        self._mock_set_magics()
+        self._mock_set_magics()  # fix magic broken by upper level init
 
 
     def _mock_set_magics(self):
         these_magics = _magics
 
-        if self._mock_methods is not None:
+        if getattr(self, "_mock_methods", None) is not None:
             these_magics = _magics.intersection(self._mock_methods)
 
             remove_magics = set()
diff -r 37905786b34b Lib/unittest/test/testmock/testmagicmethods.py
--- a/Lib/unittest/test/testmock/testmagicmethods.py	Sun Apr 12 23:24:17 2015 -0500
+++ b/Lib/unittest/test/testmock/testmagicmethods.py	Mon Apr 13 17:21:47 2015 +0200
@@ -450,5 +450,19 @@
         bar_direct = m.__rdivmod__(2)
         self.assertIsInstance(bar_direct, MagicMock)
 
+    def test_magic_in_initialization(self):
+        m = MagicMock(**{'__str__.return_value': "12"})
+        self.assertEqual(str(m), "12")
+        
+    def test_changing_magic_set_in_initialization(self):
+        m = MagicMock(**{'__str__.return_value': "12"})
+        m.__str__.return_value = "13"
+        self.assertEqual(str(m), "13")
+        
+        m = MagicMock(**{'__str__.return_value': "12"})
+        m.configure_mock(**{'__str__.return_value': "14"})
+        self.assertEqual(str(m), "14")
+
+
 if __name__ == '__main__':
     unittest.main()