Method persist_repo_topic

backend/src/git/topic.rs:632–658

(
        &self,
        mut mutation: Mutation,
        store: &S,
        child: RepoTopic,
        mut parent: RepoTopic,
        parent_topics: BTreeSet<ParentTopic>,
    )

    }

    fn persist_repo_topic<S>(
        &self,
        mut mutation: Mutation,
        store: &S,
        child: RepoTopic,
        mut parent: RepoTopic,
        parent_topics: BTreeSet<ParentTopic>,
    ) -> Result<UpsertTopicResult>
    where
        S: SaveChangesForPrefix,
    {
        let date = chrono::Utc::now();
        parent.children.insert(child.to_topic_child(date));

        let change = self.change(&child, &parent_topics, &parent, date);
        mutation.save_topic(self.repo_id, &child)?;
        mutation.save_topic(self.repo_id, &parent)?;
        mutation.add_change(self.repo_id, &change)?;
        mutation.write(store)?;

        Ok(UpsertTopicResult {
            alerts: vec![],
            matching_repo_topics: BTreeSet::new(),
            repo_topic: Some(child),
            saved: true,
        })
    }

    fn update_repo_topic<S>(
        &self,