New client creation event will always have room version set

synapse/handlers/message.py

@@ -22,7 +22,7 @@
 from twisted.internet import defer
 from twisted.internet.defer import succeed
 
-from synapse.api.constants import MAX_DEPTH, EventTypes, Membership, RoomVersions
+from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
 from synapse.api.errors import (
     AuthError,
     Codes,
@@ -279,12 +279,7 @@ def create_event(self, requester, event_dict, token_id=None, txn_id=None,
         yield self.auth.check_auth_blocking(requester.user.to_string())
 
         if event_dict["type"] == EventTypes.Create and event_dict["state_key"] == "":
-            # Set default room_version here
-            content = event_dict.setdefault("content", {})
-            room_version = content.get("room_version")
-            if not room_version:
-                room_version = RoomVersions.V1
-                content["room_version"] = room_version
+            room_version = event_dict["content"]["room_version"]
         else:
             try:
                 room_version = yield self.store.get_room_version(event_dict["room_id"])