prevent syncing with busy peers & extra logging

libethereum/BlockChainSync.cpp

@@ -534,7 +534,7 @@ bool PV60Sync::shouldGrabBlocks(std::shared_ptr<EthereumPeer> _peer) const
 
 void PV60Sync::attemptSync(std::shared_ptr<EthereumPeer> _peer)
 {
-	if (m_state != SyncState::Idle)
+	if (m_state != SyncState::Idle || _peer->m_asking != Asking::Nothing)
 	{
 		clog(NetAllDetail) << "Can't sync with this peer - outstanding asks.";
 		return;

libethereum/EthereumPeer.cpp

@@ -152,6 +152,8 @@ void EthereumPeer::requestHashes(u256 _number, unsigned _count)
 
 void EthereumPeer::requestHashes(h256 const& _lastHash)
 {
+	if (m_asking != Asking::Nothing)
+		clog(NetWarn) << "Asking hashes while requesting " << (m_asking == Asking::Nothing ? "nothing" : m_asking == Asking::State ? "state" : m_asking == Asking::Hashes ? "hashes" : m_asking == Asking::Blocks ? "blocks" : "?");
 	assert(m_asking == Asking::Nothing);
 	setAsking(Asking::Hashes);
 	RLPStream s;