eth/downloader: log hard timeouts and reset capacity

eth/downloader/downloader.go

@@ -460,6 +460,7 @@ out:
 				// 3) Amount and availability.
 				if peer := d.peers.Peer(pid); peer != nil {
 					peer.Demote()
+					glog.V(logger.Detail).Infof("%s: block delivery timeout", peer)
 				}
 			}
 			// After removing bad peers make sure we actually have sufficient peer left to keep downloading

eth/downloader/peer.go

@@ -87,6 +87,9 @@ func (p *peer) SetIdle() {
 	scale := 2.0
 	if time.Since(p.started) > blockSoftTTL {
 		scale = 0.5
+		if time.Since(p.started) > blockHardTTL {
+			scale = 1 / float64(MaxBlockFetch) // reduces capacity to 1
+		}
 	}
 	for {
 		// Calculate the new download bandwidth allowance