From 50a1f63b1b7954e25c810913a3efd37cbd731cbb Mon Sep 17 00:00:00 2001
From: Larry Ruane <larry@z.cash>
Date: Wed, 26 May 2021 16:17:55 -0600
Subject: [PATCH] when rewinding, set pindexBestHeader to the highest-work
 block index

---
 src/main.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/main.cpp b/src/main.cpp
index ad6a969b1..2b1e12373 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -5135,6 +5135,14 @@ bool RewindBlockIndex(const CChainParams& chainparams, bool& clearWitnessCaches)
 
     PruneBlockIndexCandidates();
 
+    // Ensure that pindexBestHeader points to the block index entry with the most work;
+    // setBlockIndexCandidates entries are sorted by work, highest at the end.
+    {
+        std::set<CBlockIndex*, CBlockIndexWorkComparator>::reverse_iterator it = setBlockIndexCandidates.rbegin();
+        assert(it != setBlockIndexCandidates.rend());
+        pindexBestHeader = *it;
+    }
+
     CheckBlockIndex(chainparams.GetConsensus());
 
     if (!FlushStateToDisk(chainparams, state, FLUSH_STATE_ALWAYS)) {