Set conflict? flag on unique advisory lock

The `conflict?` flag wasn't set when inserting a unique job was blocked
by an advisory lock. Now the flag is set on either a fetched duplicate,
or when the advisory lock is set.

Closes #1087

lib/oban/engines/basic.ex

@@ -330,7 +330,9 @@ defmodule Oban.Engines.Basic do
       {:ok, %Job{job | conflict?: true}}
     else
       {:error, :locked} ->
-        Changeset.apply_action(changeset, :insert)
+        with {:ok, job} <- Changeset.apply_action(changeset, :insert) do
+          %Job{job | conflict?: true}
+        end
 
       nil ->
         Repo.insert(conf, changeset, opts)

test/oban/engine_test.exs

@@ -60,19 +60,18 @@ for engine <- [Oban.Engines.Basic, Oban.Engines.Lite] do
         fun = fn ->
           Sandbox.allow(Repo, parent, self())
 
-          {:ok, %Job{id: id}} = Oban.insert(name, changeset)
+          {:ok, %Job{id: id, conflict?: conflict}} = Oban.insert(name, changeset)
 
-          id
+          {id, conflict}
         end
 
-        ids =
+        results =
           1..3
           |> Enum.map(fn _ -> Task.async(fun) end)
           |> Enum.map(&Task.await/1)
-          |> Enum.reject(&is_nil/1)
-          |> Enum.uniq()
 
-        assert 1 == length(ids)
+        assert 1 == results |> Enum.uniq_by(&elem(&1, 0)) |> length()
+        assert [false, true, true] == results |> Enum.map(&elem(&1, 1)) |> Enum.sort()
       end
 
       @tag :unique