[geary: 12/13] Common case: don't add an insert operation if inserted_ids is empty

[Michael Gratton <mjog src gnome org>]

commit d694e849987ddd5ded8f92bca0c751d1ca3c2140
Author: James Magahern <james magahern com>
Date:   Fri Jan 25 01:57:31 2019 -0800

    Common case: don't add an insert operation if inserted_ids is empty

 src/engine/app/app-conversation-monitor.vala | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/src/engine/app/app-conversation-monitor.vala b/src/engine/app/app-conversation-monitor.vala
index 510ccfa0..d9dd78af 100644
--- a/src/engine/app/app-conversation-monitor.vala
+++ b/src/engine/app/app-conversation-monitor.vala
@@ -893,7 +893,9 @@ public class Geary.App.ConversationMonitor : BaseObject {
         }
 
         // Notify about inserted messages
-        this.queue.add(new InsertOperation(this, inserted_ids));
+        if (inserted_ids.size > 0) {
+            this.queue.add(new InsertOperation(this, inserted_ids));
+        }
 
         // Notify self about removed conversations
         // NOTE: We are only notifying the conversation monitor about the removed conversations instead of