From 69c1f2c2a760fcb1c4229bff06719c73aa8cce31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Mon, 12 Feb 2018 11:54:14 +0200
Subject: [PATCH] core: force import known but rolled back blocks

---
 core/blockchain.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index 8d141fddb..e498dedef 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1070,8 +1070,12 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 		}
 		switch {
 		case err == ErrKnownBlock:
-			stats.ignored++
-			continue
+			// Block and state both already known. However if the current block is below
+			// this number we did a rollback and we should reimport it nonetheless.
+			if bc.CurrentBlock().NumberU64() >= block.NumberU64() {
+				stats.ignored++
+				continue
+			}
 
 		case err == consensus.ErrFutureBlock:
 			// Allow up to MaxFuture second in the future blocks. If this limit is exceeded