Enable user timelines.

lib/pleroma/web/twitter_api/twitter_api.ex

@@ -215,10 +215,18 @@ defmodule Pleroma.Web.TwitterAPI.TwitterAPI do
     end
   end
 
+  def get_by_id_or_nickname(id_or_nickname) do
+    if !is_integer(id_or_nickname) && :error == Integer.parse(id_or_nickname) do
+      Repo.get_by(User, nickname: id_or_nickname)
+    else
+      Repo.get(User, id_or_nickname)
+    end
+  end
+
   def get_user(user \\ nil, params) do
     case params do
       %{"user_id" => user_id} ->
-        case target = Repo.get(User, user_id) do
+        case target = get_by_id_or_nickname(user_id) do
           nil ->
             {:error, "No user with such user_id"}
           _ ->