merge queue: embarking unstable (0507eca) and #8353 together

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -883,6 +883,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             return Ok(None);
         }
 
+        // Fast-path for the split slot (which usually corresponds to the finalized slot).
+        let split = self.store.get_split_info();
+        if request_slot == split.slot {
+            return Ok(Some(split.state_root));
+        }
+
         // Try an optimized path of reading the root directly from the head state.
         let fast_lookup: Option<Hash256> = self.with_head(|head| {
             if head.beacon_block.slot() <= request_slot {

beacon_node/beacon_chain/tests/store_tests.rs

@@ -3155,6 +3155,10 @@ async fn weak_subjectivity_sync_test(
             .get_state(&state_root, Some(slot), CACHE_STATE_IN_TESTS)
             .unwrap()
             .unwrap();
+        assert_eq!(
+            state_root,
+            beacon_chain.state_root_at_slot(slot).unwrap().unwrap()
+        );
         assert_eq!(state.slot(), slot);
         assert_eq!(state.canonical_root().unwrap(), state_root);
     }