Revert "Blacklist mildly naughty peers (don't disconnect)"

This reverts commit 8d0fd7649d26825b88f2cf9442053a1a8f391a8a.

trinity/sync/common/headers.py

@@ -9,7 +9,6 @@
     FrozenSet,
     Generic,
     Sequence,
-    Set,
     Tuple,
     Type,
 )
@@ -81,8 +80,6 @@ class SkeletonSyncer(BaseService, Generic[TChainPeer]):
 
     _fetched_headers: 'asyncio.Queue[Tuple[BlockHeader, ...]]'
 
-    _blacklist: Set[TChainPeer] = set()
-
     def __init__(self,
                  chain: BaseAsyncChain,
                  db: BaseAsyncHeaderDB,
@@ -127,17 +124,14 @@ async def _quietly_fetch_full_skeleton(self) -> None:
             await self._fetch_full_skeleton()
         except ValidationError as exc:
             self.logger.debug(
-                "Exiting sync %s due to validation error: %s",
+                "Exiting sync and booting %s due to validation error: %s",
                 self.peer,
                 exc,
             )
-            # TODO bring back booting eventually?
-            #await self.peer.disconnect(DisconnectReason.subprotocol_error)
-            self._blacklist.add(self.peer)
+            await self.peer.disconnect(DisconnectReason.subprotocol_error)
         except TimeoutError:
             self.logger.warning("Timeout waiting for header batch from %s, halting sync", self.peer)
-            #await self.peer.disconnect(DisconnectReason.timeout)
-            self._blacklist.add(self.peer)
+            await self.peer.disconnect(DisconnectReason.timeout)
 
     async def _fetch_full_skeleton(self) -> None:
         """
@@ -454,16 +448,14 @@ async def _fetch_headers_from(
             return tuple()
         except TimeoutError:
             self.logger.warning("Timeout waiting for header batch from %s, aborting sync", peer)
-            #await peer.disconnect(DisconnectReason.timeout)
-            self._blacklist.add(self.peer)
+            await peer.disconnect(DisconnectReason.timeout)
             return tuple()
         except ValidationError as err:
             self.logger.warning(
                 "Invalid header response sent by peer %s disconnecting: %s",
                 peer, err,
             )
-            #await peer.disconnect(DisconnectReason.subprotocol_error)
-            self._blacklist.add(self.peer)
+            await peer.disconnect(DisconnectReason.subprotocol_error)
             return tuple()
 
         if not headers:
@@ -833,8 +825,6 @@ async def _build_skeleton(self) -> None:
         """
         # iterator yields the peer with the highest TD in our pool
         async for peer in self._tip_monitor.wait_tip_info():
-            if peer in SkeletonSyncer._blacklist:
-                continue
             try:
                 await self._validate_peer_is_ahead(peer)
             except _PeerBehind: