cron: remove unused imports

wcs/qommon/cron.py

@@ -17,15 +17,12 @@
 import os
 import signal
 import time
-import traceback
 try:
     import dl
 except ImportError:
     dl = None
 import sys
 
-from storage import StorableObject
-
 parent_killed = False
 
 def stop_cron_process(*args):