Misc typing fixes for `tests`, part 1 of N (#11323)

* Annotate HomeserverTestCase.servlets
* Correct annotation of federation_auth_origin
* Use AnyStr custom_headers instead of a Union

This allows (str, str) and (bytes, bytes).
This disallows (str, bytes) and (bytes, str)

* DomainSpecificString.SIGIL is a ClassVar

1 files changed, 2 insertions, 1 deletions

diff --git a/synapse/types.py b/synapse/types.py

index 9d7a675662..fb72f19343 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -19,6 +19,7 @@ from collections import namedtuple
 from typing import (
     TYPE_CHECKING,
     Any,
+    ClassVar,
     Dict,
     Mapping,
     MutableMapping,
@@ -219,7 +220,7 @@ class DomainSpecificString(metaclass=abc.ABCMeta):
         'domain' : The domain part of the name
     """
 
-    SIGIL: str = abc.abstractproperty()  # type: ignore
+    SIGIL: ClassVar[str] = abc.abstractproperty()  # type: ignore
 
     localpart = attr.ib(type=str)
     domain = attr.ib(type=str)