Revise EE peer penalites (#3485)

## Issue Addressed

NA

## Proposed Changes

Don't penalize peers for errors that might be caused by an honest optimistic node.

## Additional Info

NA

Author: paulhauner

beacon_node/beacon_chain/src/block_verification.rs

@@ -349,13 +349,27 @@ impl ExecutionPayloadError {
         // always forced to consider here whether or not to penalize a peer when
         // we add a new error condition.
         match self {
+            // The peer has nothing to do with this error, do not penalize them.
             ExecutionPayloadError::NoExecutionConnection => false,
+            // The peer has nothing to do with this error, do not penalize them.
             ExecutionPayloadError::RequestFailed(_) => false,
-            ExecutionPayloadError::RejectedByExecutionEngine { .. } => true,
+            // An honest optimistic node may propagate blocks which are rejected by an EE, do not
+            // penalize them.
+            ExecutionPayloadError::RejectedByExecutionEngine { .. } => false,
+            // This is a trivial gossip validation condition, there is no reason for an honest peer
+            // to propagate a block with an invalid payload time stamp.
             ExecutionPayloadError::InvalidPayloadTimestamp { .. } => true,
-            ExecutionPayloadError::InvalidTerminalPoWBlock { .. } => true,
-            ExecutionPayloadError::InvalidActivationEpoch { .. } => true,
-            ExecutionPayloadError::InvalidTerminalBlockHash { .. } => true,
+            // An honest optimistic node may propagate blocks with an invalid terminal PoW block, we
+            // should not penalized them.
+            ExecutionPayloadError::InvalidTerminalPoWBlock { .. } => false,
+            // This condition is checked *after* gossip propagation, therefore penalizing gossip
+            // peers for this block would be unfair. There may be an argument to penalize RPC
+            // blocks, since even an optimistic node shouldn't verify this block. We will remove the
+            // penalties for all block imports to keep things simple.
+            ExecutionPayloadError::InvalidActivationEpoch { .. } => false,
+            // As per `Self::InvalidActivationEpoch`.
+            ExecutionPayloadError::InvalidTerminalBlockHash { .. } => false,
+            // Do not penalize the peer since it's not their fault that *we're* optimistic.
             ExecutionPayloadError::UnverifiedNonOptimisticCandidate => false,
         }
     }