https://github.com/google/oauth2client/issues/443

Allow for binary code values in oauth_flow.step2_exchange(code). An issue with Python 3 since the code will be binary.
A simple test that binary values are allowed. credentials = self.flow.step2_exchange(b'some random code', http=http)

tox -e py34  -- tests.test_client:OAuth2WebServerFlowTest.test_exchange_success_binary_code

oauth2client/client.py

@@ -2069,7 +2069,7 @@ def step2_exchange(self, code=None, http=None, device_flow_info=None):
 
         if code is None:
             code = device_flow_info.device_code
-        elif not isinstance(code, six.string_types):
+        elif not isinstance(code, (six.string_types, six.binary_type)):
             if 'code' not in code:
                 raise FlowExchangeError(code.get(
                     'error', 'No code was supplied in the query parameters.'))

tests/test_client.py

@@ -1201,6 +1201,21 @@ def test_exchange_success(self):
         self.assertEqual('dummy_revoke_uri', credentials.revoke_uri)
         self.assertEqual(set(['foo']), credentials.scopes)
 
+    def test_exchange_success_binary_code(self):
+        payload = (b'{'
+                   b'  "access_token":"SlAV32hkKG",'
+                   b'  "expires_in":3600,'
+                   b'  "refresh_token":"8xLOxBtZp8"'
+                   b'}')
+
+        http = HttpMockSequence([({'status': '200'}, payload)])
+        credentials = self.flow.step2_exchange(b'some random code', http=http)
+        self.assertEqual('SlAV32hkKG', credentials.access_token)
+        self.assertNotEqual(None, credentials.token_expiry)
+        self.assertEqual('8xLOxBtZp8', credentials.refresh_token)
+        self.assertEqual('dummy_revoke_uri', credentials.revoke_uri)
+        self.assertEqual(set(['foo']), credentials.scopes)
+
     def test_exchange_dictlike(self):
         class FakeDict(object):
             def __init__(self, d):