Bugfix: Handle networks with TTD=0 (e.g. withdrawal devnets)

beacon_chain/eth1/eth1_monitor.nim

@@ -1458,9 +1458,12 @@ proc findTerminalBlock(provider: Web3DataProviderRef,
       provider.web3.provider.eth_getBlockByNumber("latest", false))
     b = await next(a)
 
+  if a.number.uint64 == 0 and a.totalDifficulty >= ttd:
+    return a
+
   while true:
-    let one = a.totalDifficulty > ttd
-    let two = b.totalDifficulty > ttd
+    let one = a.totalDifficulty >= ttd
+    let two = b.totalDifficulty >= ttd
     if one != two:
       step = step div -2i64
       if step == 0:

scripts/run-nimbus-eth2-in-withdrawal-testnet.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+if [ -z "$1" ]; then
+  echo "Usage: run-nimbus-eth2-in-withdrawal-testnet.sh <network-metadata-dir>"
+  exit 1
+fi
+
+if [ ! -d "$1" ]; then
+  echo "Please supply a valid network metadata directory"
+  exit 1
+fi
+
+set -Eeu
+
+NETWORK=$(cd "$1"; pwd)
+
+cd $(dirname "$0")
+
+source repo_paths.sh
+
+DATA_DIR="$(create_data_dir_for_network "$NETWORK")"
+
+JWT_TOKEN="$DATA_DIR/jwt-token"
+create_jwt_token "$JWT_TOKEN"
+
+"$BUILD_DIR/nimbus_beacon_node" \
+  --non-interactive \
+  --udp-port=19000 \
+  --tcp-port=19000 \
+  --network="$NETWORK" \
+  --log-level=DEBUG \
+  --data-dir="$DATA_DIR/nimbus_bn" \
+  --el=http://localhost:18550/ \
+  --rest:on \
+  --rest-port=15052 \
+  --metrics=on \
+  --metrics-port=18008 \
+  --doppelganger-detection=no \
+  --jwt-secret="$JWT_TOKEN"