Reset beat schedule to upgrade to UTC. Closes #844

celery/beat.py

@@ -342,10 +342,12 @@ class PersistentScheduler(Scheduler):
         else:
             if '__version__' not in self._store:
                 self._store.clear()   # remove schedule at 2.2.2 upgrade.
+            if 'utc' not in self._store:
+                self._store.clear()   # remove schedule at 3.0.1 upgrade.
         entries = self._store.setdefault('entries', {})
         self.merge_inplace(self.app.conf.CELERYBEAT_SCHEDULE)
         self.install_default_entries(self.schedule)
-        self._store['__version__'] = __version__
+        self._store.update(__version__=__version__, utc=True)
         self.sync()
         debug('Current schedule:\n' + '\n'.join(repr(entry)
                                     for entry in entries.itervalues()))