fix: trash no-op addition messages

This partially restores the fix from c9cf2b7f2e
that was removed during the addition of new group consistency at de63527d94
but only for "Member added" messages.

Multiple "Member added" messages happen
when the same QR code is processed multiple times
by multiple devices.

src/receive_imf/tests.rs

@@ -5049,6 +5049,32 @@ async fn test_unarchive_on_member_removal() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_no_op_member_added_is_trash() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+    let alice_chat_id = alice
+        .create_group_with_members(ProtectionStatus::Unprotected, "foos", &[bob])
+        .await;
+    send_text_msg(alice, alice_chat_id, "populate".to_string()).await?;
+    let msg = alice.pop_sent_msg().await;
+    bob.recv_msg(&msg).await;
+    let bob_chat_id = bob.get_last_msg().await.chat_id;
+    bob_chat_id.accept(bob).await?;
+
+    let fiona_id = Contact::create(alice, "", "fiona@example.net").await?;
+    add_contact_to_chat(alice, alice_chat_id, fiona_id).await?;
+    let msg = alice.pop_sent_msg().await;
+
+    let fiona_id = Contact::create(bob, "", "fiona@example.net").await?;
+    add_contact_to_chat(bob, bob_chat_id, fiona_id).await?;
+    bob.recv_msg_trash(&msg).await;
+    let contacts = get_chat_contacts(bob, bob_chat_id).await?;
+    assert_eq!(contacts.len(), 3);
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn test_forged_from() -> Result<()> {
     let mut tcm = TestContextManager::new();