message: Take out redundant comment
  The error messeage already says what the problem is we
  don't need another code comment to inform the dev of what is
  happening here.
diff: @@ -5978,7 +5978,7 @@ bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv, int64_t
  {
  LOCK(cs_main);
  BlockMap::iterator mi = mapBlockIndex.find(inv.hash);
  - if (mi == mapBlockIndex.end()) // This block does not even exist
  + if (mi == mapBlockIndex.end())
  {
  Misbehaving(pfrom->GetId(), 100);
  return error("Peer %s (%d) requested nonexistent block %s\n", pfrom->addrName.c_str(), pfrom->id, inv.hash.ToString());
  