Revert "Small simplification of startHandlingForkChoice (erigontech#4636

)" (erigontech#4649)

This reverts commit cc75387.

eth/stagedsync/stage_headers.go

@@ -321,7 +321,34 @@ func startHandlingForkChoice(
 	cfg.hd.BeaconRequestList.Remove(requestId)
 
 	headerNumber := header.Number.Uint64()
-	cfg.hd.UpdateTopSeenHeightPoS(headerNumber)
+	// If header is canonical, then no reorgs are required
+	canonicalHash, err := rawdb.ReadCanonicalHash(tx, headerNumber)
+	if err != nil {
+		log.Warn(fmt.Sprintf("[%s] Fork choice err (reading canonical hash of %d)", s.LogPrefix(), headerNumber), "err", err)
+		cfg.hd.BeaconRequestList.Remove(requestId)
+		return nil, err
+	}
+
+	if headerHash == canonicalHash {
+		log.Info(fmt.Sprintf("[%s] Fork choice on previously known block", s.LogPrefix()))
+		cfg.hd.BeaconRequestList.Remove(requestId)
+		rawdb.WriteForkchoiceHead(tx, forkChoice.HeadBlockHash)
+		canonical, err := safeAndFinalizedBlocksAreCanonical(forkChoice, s, tx, cfg)
+		if err != nil {
+			log.Warn(fmt.Sprintf("[%s] Fork choice err", s.LogPrefix()), "err", err)
+			return nil, err
+		}
+		if canonical {
+			return &privateapi.PayloadStatus{
+				Status:          remote.EngineStatus_VALID,
+				LatestValidHash: headerHash,
+			}, nil
+		} else {
+			return &privateapi.PayloadStatus{
+				CriticalError: &privateapi.InvalidForkchoiceStateErr,
+			}, nil
+		}
+	}
 
 	if cfg.memoryOverlay && headerHash == cfg.hd.GetNextForkHash() {
 		log.Info("Flushing in-memory state")
@@ -345,6 +372,7 @@ func startHandlingForkChoice(
 		}
 	}
 
+	cfg.hd.UpdateTopSeenHeightPoS(headerNumber)
 	forkingPoint := uint64(0)
 	if headerNumber > 0 {
 		parent, err := headerReader.Header(ctx, tx, header.ParentHash, headerNumber-1)