Enable redefined-variable-type lint

.pylintrc

@@ -31,9 +31,8 @@ notes=FIXME,XXX
 # disable=cyclic-import suppressions.
 #TODO: Enable too-many-instance-attributes
 #TODO: Enable too-many-lines
-#TODO: Enable redefined-variable-type
 #TODO: Enable import-error
 #TODO: Enable useless-else-on-loop
 #TODO: Enable too-many-nested-blocks
 
-disable=missing-docstring,too-few-public-methods,no-init,duplicate-code,invalid-name,locally-disabled,protected-access,no-name-in-module,wrong-import-order,cyclic-import,too-many-instance-attributes,too-many-lines,redefined-variable-type,import-error,useless-else-on-loop,too-many-nested-blocks
+disable=missing-docstring,too-few-public-methods,no-init,duplicate-code,invalid-name,locally-disabled,protected-access,no-name-in-module,wrong-import-order,cyclic-import,too-many-instance-attributes,too-many-lines,import-error,useless-else-on-loop,too-many-nested-blocks

src/python/grpcio/grpc/_channel.py

@@ -849,7 +849,10 @@ def _poll_connectivity(state, channel, initial_try_to_connect):
                     _common.CYGRPC_CONNECTIVITY_STATE_TO_CHANNEL_CONNECTIVITY[
                         connectivity])
                 if not state.delivering:
-                    callbacks = _deliveries(state)
+                    # NOTE(nathaniel): The field is only ever used as a
+                    # sequence so it's fine that both lists and tuples are
+                    # assigned to it.
+                    callbacks = _deliveries(state)  # pylint: disable=redefined-variable-type
                     if callbacks:
                         _spawn_delivery(state, callbacks)