more explicit message

packer/rpc/ui.go

@@ -37,7 +37,7 @@ func (u *Ui) Ask(query string) (result string, err error) {
 
 func (u *Ui) Error(message string) {
 	if err := u.client.Call("Ui.Error", message, new(interface{})); err != nil {
-		log.Printf("Error in Ui RPC call: %s", err)
+		log.Printf("Error in Ui.Error RPC call: %s", err)
 	}
 }
 
@@ -48,25 +48,25 @@ func (u *Ui) Machine(t string, args ...string) {
 	}
 
 	if err := u.client.Call("Ui.Machine", rpcArgs, new(interface{})); err != nil {
-		log.Printf("Error in Ui RPC call: %s", err)
+		log.Printf("Error in Ui.Machine RPC call: %s", err)
 	}
 }
 
 func (u *Ui) Message(message string) {
 	if err := u.client.Call("Ui.Message", message, new(interface{})); err != nil {
-		log.Printf("Error in Ui RPC call: %s", err)
+		log.Printf("Error in Ui.Message RPC call: %s", err)
 	}
 }
 
 func (u *Ui) Say(message string) {
 	if err := u.client.Call("Ui.Say", message, new(interface{})); err != nil {
-		log.Printf("Error in Ui RPC call: %s", err)
+		log.Printf("Error in Ui.Say RPC call: %s", err)
 	}
 }
 
 func (u *Ui) ProgressBar() packer.ProgressBar {
 	if err := u.client.Call("Ui.ProgressBar", new(interface{}), new(interface{})); err != nil {
-		log.Printf("Error in Ui RPC call: %s", err)
+		log.Printf("Error in Ui.ProgressBar RPC call: %s", err)
 	}
 	return u // Ui is also a progress bar !!
 }