waits in case master lost connection

weed/wdclient/masterclient.go

@@ -36,6 +36,9 @@ func NewMasterClient(grpcDialOption grpc.DialOption, clientType string, clientHo
 }
 
 func (mc *MasterClient) GetMaster() string {
+	for mc.currentMaster == "" {
+		time.Sleep(time.Duration(rand.Int31n(200)) * time.Millisecond)
+	}
 	return mc.currentMaster
 }