Simplified implementation of is_due.

There is no reason anymore to call out to _check_hour_minute anymore, since the
due calculation is now so trivial.

celery/task/schedules.py

@@ -217,11 +217,7 @@ class crontab(schedule):
         last = now - last_run_at
         due, when = False, 1
         if last.days > 0 or last.seconds > 60:
-            if now.isoweekday() in self.day_of_week:
-                due, when = self._check_hour_minute(now)
-        return due, when
-
-    def _check_hour_minute(self, now):
-        due = now.hour in self.hour and now.minute in self.minute
-        when = 1
+            due = now.isoweekday() in self.day_of_week and \
+                  now.hour in self.hour and \
+                  now.minute in self.minute
         return due, when