Fix missed post_work_hook invocation

There are two places where we can be done, depending on the invocation,
so there was a situation where the post_work hook wasn't firing on
completed work.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
diff --git a/grokmirror/pull.py b/grokmirror/pull.py
index 7472298..d205b69 100755
--- a/grokmirror/pull.py
+++ b/grokmirror/pull.py
@@ -1282,6 +1282,8 @@
             if not runonce and not len(mws) and q_todo.empty() and q_pull.empty() and time.time() - lastrun >= refresh:
                 if done:
                     update_manifest(config, done)
+                    if post_work_hook:
+                        run_post_work_complete_hook(config)
                 mw = mp.Process(target=manifest_worker, args=(config, q_mani, nomtime))
                 nomtime = False
                 mw.daemon = True