test: cover replay_events_after None-message branch (135->132)

Author: perhapzz

tests/shared/test_streamable_http.py

@@ -2312,12 +2312,13 @@ async def test_replay_events_after_replays_messages():
     stream_id = "stream-1"
     msg1: types.JSONRPCMessage = types.JSONRPCResponse(jsonrpc="2.0", id="1", result={"first": True})
     msg2: types.JSONRPCMessage = types.JSONRPCResponse(jsonrpc="2.0", id="2", result={"second": True})
-    # Store: priming event (None), then two real messages
+    # Store: priming event (None), real message, another None (priming), then real message
     eid0 = await store.store_event(stream_id, None)
     eid1 = await store.store_event(stream_id, msg1)
+    _eid_none = await store.store_event(stream_id, None)
     eid2 = await store.store_event(stream_id, msg2)
 
-    # Replay after priming event — should get both messages
+    # Replay after priming event — should get only real messages, skipping None
     replayed: list[EventMessage] = []
 
     async def callback(event_msg: EventMessage) -> None: