From c546cab03fa4710636dbef214d9c0ea773ee7234 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Sun, 19 Jan 2020 22:08:35 +1100
Subject: [PATCH] Ignore duplicate blocks in fork choice

---
 eth2/proto_array_fork_choice/src/proto_array.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/eth2/proto_array_fork_choice/src/proto_array.rs b/eth2/proto_array_fork_choice/src/proto_array.rs
index 978a8d6f1e..6653221aa1 100644
--- a/eth2/proto_array_fork_choice/src/proto_array.rs
+++ b/eth2/proto_array_fork_choice/src/proto_array.rs
@@ -130,6 +130,11 @@ impl ProtoArray {
         justified_epoch: Epoch,
         finalized_epoch: Epoch,
     ) -> Result<(), Error> {
+        // If the block is already known, simply ignore it.
+        if self.indices.contains_key(&root) {
+            return Ok(());
+        }
+
         let node_index = self.nodes.len();
 
         let node = ProtoNode {