Fix FakeSwiftCall partial env copy for None values

None values in the request environ should be copied, not replaced with
the dummy value.

Related-Change: I332ce724aa10287800cbec8ca21aacc3bbd3c22a
Change-Id: Id78ac1cac833f9284946cd364b3f95341afcb235

test/unit/common/middleware/helpers.py

@@ -78,7 +78,9 @@ class FakeSwiftCall(object):
         # mutable values. However, some things (e.g. EncInputWrapper) won't
         # deepcopy. To avoid a confusing mixed of copied and original
         # values, replace un-copied values with DUMMY_VALUE.
-        if isinstance(value, (bool, int, float, str, bytes)):
+        if value is None:
+            return value
+        elif isinstance(value, (bool, int, float, str, bytes)):
             return value
         elif isinstance(value, (list, tuple, set)):
             return value.__class__([self._partial_copy(v) for v in value])

test/unit/common/middleware/test_helpers.py

@@ -54,7 +54,8 @@ class TestFakeSwiftCall(unittest.TestCase):
                     'gen4': range(4),
                     'l': a_list
                 },
-                'z': d_dict
+                'z': d_dict,
+                'null': None,
             },
         }
         call = FakeSwiftCall(req)
@@ -80,7 +81,8 @@ class TestFakeSwiftCall(unittest.TestCase):
                         'gen4': FakeSwiftCall.DUMMY_VALUE,
                         'l': [(1, 2), {10, FakeSwiftCall.DUMMY_VALUE}]
                     },
-                    'z': {'a': 'b'}
+                    'z': {'a': 'b'},
+                    'null': None,
                 },
             },
             call.env['deep.mutable'])