Updating the post type slug does not always work

[jaymcp]

Updating the slug for the petitions post type via Settings -> Permalinks does not always update the slug correctly. Sometimes the setting just does not change.
Even when the setting updates correctly, existing entries in the post type do not have their post_type updated correctly.
This may be due to a race condition.

We should review or revisit how we update the setting, and how we trigger the post type updates when the slug changes.