Add some more type hints.

synapse/handlers/oidc_handler.py

@@ -865,11 +865,11 @@ class OidcHandler(BaseHandler):
         remote_user_id = str(remote_user_id)
 
         # first of all, check if we already have a mapping for this user
-        registered_user_id = await self._sso_handler.get_sso_user_by_remote_user_id(
+        previously_registered_user_id = await self._sso_handler.get_sso_user_by_remote_user_id(
             self._auth_provider_id, remote_user_id,
         )
-        if registered_user_id:
+        if previously_registered_user_id:
-            return registered_user_id
+            return previously_registered_user_id
 
         # Otherwise, generate a new user.
         try:

synapse/handlers/saml_handler.py

@@ -250,11 +250,11 @@ class SamlHandler(BaseHandler):
 
         with (await self._mapping_lock.queue(self._auth_provider_id)):
             # first of all, check if we already have a mapping for this user
-            registered_user_id = await self._sso_handler.get_sso_user_by_remote_user_id(
+            previously_registered_user_id = await self._sso_handler.get_sso_user_by_remote_user_id(
                 self._auth_provider_id, remote_user_id,
             )
-            if registered_user_id:
+            if previously_registered_user_id:
-                return registered_user_id
+                return previously_registered_user_id
 
             # backwards-compatibility hack: see if there is an existing user with a
             # suitable mapping from the uid

synapse/server.py

@@ -392,7 +392,7 @@ class HomeServer(metaclass=abc.ABCMeta):
             return FollowerTypingHandler(self)
 
     @cache_in_self
-    def get_sso_handler(self):
+    def get_sso_handler(self) -> SsoHandler:
         return SsoHandler(self)
 
     @cache_in_self