Cannot do trusted sync from Prysm

[anonqoder]

Prysm beacon is running:

$ curl http://127.0.0.1:4500/eth/v1/beacon/blocks/head/root | jq

{
  "data": {
    "root": "0x42e28e33fb9665dc1a0da1b0bac8a141463a37aa5e8db6662c75f2488f9d73b1"
  },
  "execution_optimistic": false
}

But Nimbus is unable to sync from it:

$ ./nimbus_beacon_node trustedNodeSync --network:prater --data-dir=/data/nimbus --trusted-node-url=http://localhost:4500

NOT 2022-05-13 16:08:25.984+01:00 Starting trusted node sync                 databaseDir=/data/nimbus/db restUrl=http://localhost:4500 blockId=finalized backfill=true reindex=false
ERR 2022-05-13 16:08:27.021+01:00 Unable to download genesis block root      error="Unable to decode REST response, error [Serialization error]" restUrl=http://localhost:4500

[zah]

This should be fixed by #3647