SSS: don't block if there is new extension data

src/api/client_server/sync/msc4186.rs

@@ -499,9 +499,31 @@ pub(crate) async fn sync_events_v5_route(
         }
     }
 
+    let extensions = sync_events::v5::response::Extensions {
+        to_device,
+        e2ee: e2ee.unwrap_or_default(),
+        account_data: account_data.unwrap_or_default(),
+        receipts: sync_events::v5::response::Receipts {
+            rooms: BTreeMap::new(),
+        },
+        typing: sync_events::v5::response::Typing {
+            rooms: BTreeMap::new(),
+        },
+    };
+
+    let extensions_empty = extensions
+        .to_device
+        .as_ref()
+        .is_none_or(|to_device| to_device.events.is_empty())
+        && extensions.e2ee.device_lists.is_empty()
+        && extensions.account_data.is_empty()
+        && extensions.receipts.is_empty()
+        && extensions.typing.is_empty();
+
     if rooms
         .iter()
         .all(|(_, r)| r.timeline.is_empty() && r.required_state.is_empty())
+        && extensions_empty
     {
         // Hang a few seconds so requests are not spammed
         // Stop hanging if new info arrives
@@ -520,17 +542,7 @@ pub(crate) async fn sync_events_v5_route(
         pos: next_batch.to_string(),
         lists,
         rooms,
-        extensions: sync_events::v5::response::Extensions {
+        extensions,
-            to_device,
-            e2ee: e2ee.unwrap_or_default(),
-            account_data: account_data.unwrap_or_default(),
-            receipts: sync_events::v5::response::Receipts {
-                rooms: BTreeMap::new(),
-            },
-            typing: sync_events::v5::response::Typing {
-                rooms: BTreeMap::new(),
-            },
-        },
     }))
 }