mypy: Remove some now-unused type: ignores.

zerver/decorator.py

@@ -461,12 +461,12 @@ def authenticated_rest_api_view(is_webhook=False):
                 return json_unauthorized(e.msg)
             request.user = profile
             if is_remote_server(role):
-                assert isinstance(profile, RemoteZulipServer)  # type: ignore # https://github.com/python/mypy/issues/2957
+                assert isinstance(profile, RemoteZulipServer)
                 request._email = "zulip-server:" + role
                 profile.rate_limits = ""
                 process_client(request, profile, remote_server_request=True)
             else:
-                assert isinstance(profile, UserProfile)  # type: ignore # https://github.com/python/mypy/issues/2957
+                assert isinstance(profile, UserProfile)
                 request._email = profile.email
                 process_client(request, profile)
             # Apply rate limiting

zerver/lib/actions.py

@@ -1164,7 +1164,7 @@ def extract_recipients(s):
         data = s
 
     if isinstance(data, six.string_types):
-        data = data.split(',')  # type: ignore # https://github.com/python/typeshed/pull/138
+        data = data.split(',')
 
     if not isinstance(data, list):
         raise ValueError("Invalid data type for recipients")