Don't post full "backlog" of scheduled topics

This will probably only ever be relevant in development environments,
but we don't want the topic scheduler to always post a full backlog of
scheduled topics when it hasn't run for a while. For example, if a dev
environment has a daily scheduled topic set up, but the VM is not
launched for a week, the next time the "post scheduled topics" cronjob
runs, it will post all 7 of the backlogged topics.

This commit changes the script so that it advances the schedule to the
next *future* occurrence, instead of continuing the backlog.

tildes/scripts/post_scheduled_topics.py

@@ -36,7 +36,7 @@ def post_scheduled_topics(config_path: str) -> None:
 
     while due_topic:
         db_session.add(due_topic.create_topic())
-        due_topic.advance_schedule()
+        due_topic.advance_schedule_to_future()
         db_session.add(due_topic)
         db_session.commit()
 

tildes/tildes/models/topic/topic_schedule.py

@@ -106,10 +106,10 @@ class TopicSchedule(DatabaseModel):
 
         return topic
 
-    def advance_schedule(self) -> None:
-        """Advance the schedule, setting next_post_time appropriately."""
+    def advance_schedule_to_future(self) -> None:
+        """Advance the schedule to the next future occurrence."""
         if self.recurrence_rule:
             rule = self.recurrence_rule.replace(dtstart=self.next_post_time)
-            self.next_post_time = rule.after(self.next_post_time)
+            self.next_post_time = rule.after(utc_now())
         else:
             self.next_post_time = None