Improve hairpin log messages

prog/weaver/main.go

@@ -231,7 +231,8 @@ func main() {
 
 	if bridge != nil {
 		if err := weavenet.DetectHairpin("vethwe-bridge", Log); err != nil {
-			Log.Errorf("DetectHairpin failed: %s", err)
+			Log.Errorf("Setting may cause connectivity issues : %s", err)
+			Log.Infof("Hairpin mode may have been enabled by other software on this machine")
 		}
 	}
 

router/fastdp.go

@@ -1224,7 +1224,7 @@ func (fastdp *FastDatapath) send(fops FlowOp, frame []byte, lock *fastDatapathLo
 	}
 
 	if fastdp.isHairpinFlow(&flow) {
-		log.Error("Vetoed installation of hairpin flow ", flow)
+		log.Warning("Vetoed installation of hairpin flow ", flow)
 		return
 	}