fix long period task will never be triggered

django_celery_beat/schedulers.py

@@ -84,13 +84,7 @@ def __init__(self, model, app=None):
         self.model = model
 
         if not model.last_run_at:
-            model.last_run_at = self._default_now()
-            # if last_run_at is not set and
-            # model.start_time last_run_at should be in way past.
-            # This will trigger the job to run at start_time
-            # and avoid the heap block.
-            if self.model.start_time:
-                model.last_run_at = model.last_run_at \
+            model.last_run_at = self._default_now() \
                     - datetime.timedelta(days=365 * 30)
 
         self.last_run_at = model.last_run_at