ConversationView: fix last_status.account being empty, fix current user being included in group conversations

lib/pleroma/web/mastodon_api/views/conversation_view.ex

@@ -34,14 +34,22 @@ defmodule Pleroma.Web.MastodonAPI.ConversationView do
 
     activity = Activity.get_by_id_with_object(last_activity_id)
 
+    # Conversations return all users except current user when current user is not only participant
+    users = if length(participation.recipients) > 1 do
+      Enum.reject(participation.recipients, &(&1.id == user.id))
+    else
+      participation.recipients
+    end
+
     %{
       id: participation.id |> to_string(),
-      accounts: render(AccountView, "index.json", users: participation.recipients, for: user),
+      accounts: render(AccountView, "index.json", users: users, for: user),
       unread: !participation.read,
       last_status:
         render(StatusView, "show.json",
           activity: activity,
-          direct_conversation_id: participation.id
+          direct_conversation_id: participation.id,
+          for: user
         )
     }
   end