Bug: Versioned custom models fail with AttributeError on missing in_navigation property

[fsbraun]

Issue

When registering a custom model for versioning and previewing or editing a version of that custom model, the djangocms_versioning.cms_toolbar raises an AttributeError missing the in_navigation attribute of the custom model.

djangocms-versioning provides its own page toolbar which unlike the original page toolbar of django CMS does also assume that the viewed/edited model is of type PageContent which it is not for custom models. This happens if the custom model is apphooked.

Reference

• Some bugfixes to incorporate fsbraun/djangocms-blog#4