Treat MRF rejects as success in Oban worker

lib/pleroma/workers/receiver_worker.ex

@@ -9,6 +9,11 @@ defmodule Pleroma.Workers.ReceiverWorker do
 
   @impl Oban.Worker
   def perform(%Job{args: %{"op" => "incoming_ap_doc", "params" => params}}) do
-    Federator.perform(:incoming_ap_doc, params)
+    with {:ok, res} <- Federator.perform(:incoming_ap_doc, params) do
+      {:ok, res}
+    else
+      {:error, {:reject, reason}} -> {:cancel, reason}
+      e -> e
+    end
   end
 end

test/pleroma/workers/receiver_worker_test.exs

@@ -0,0 +1,25 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Workers.ReceiverWorkerTest do
+  use Pleroma.DataCase, async: true
+  use Oban.Testing, repo: Pleroma.Repo
+
+  import Mock
+  import Pleroma.Factory
+
+  alias Pleroma.Workers.ReceiverWorker
+
+  test "it ignores MRF reject" do
+    params = insert(:note).data
+
+    with_mock Pleroma.Web.ActivityPub.Transmogrifier,
+      handle_incoming: fn _ -> {:reject, "MRF"} end do
+      assert {:cancel, "MRF"} =
+               ReceiverWorker.perform(%Oban.Job{
+                 args: %{"op" => "incoming_ap_doc", "params" => params}
+               })
+    end
+  end
+end