Revert "Tidy ancestor iterators"

This reverts commit 5079c25bb2.

Accidental push to master.. my bad!

beacon_node/rpc/src/attestation.rs

@@ -40,11 +40,7 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
         // verify the slot, drop lock on state afterwards
         {
             let slot_requested = req.get_slot();
-            // TODO: this whole module is legacy and not maintained well.
-            let state = &self
-                .chain
-                .speculative_state()
-                .expect("This is legacy code and should be removed");
+            let state = &self.chain.current_state();
 
             // Start by performing some checks
             // Check that the AttestationData is for the current slot (otherwise it will not be valid)