As follow up for MDL-37762 and quick fix MDL-39127. There are a couple more issues with showing course categories in navbar:

1. /badges/view.php is modifying navigation for some reason and the categories do not appear there

2. We need to consider all three settings when deciding if and how to add course categories to navbar:

• Show course categories (navshowcategories) Default: Yes Show course categories in the navigation bar and navigation blocks. This does not occur with courses the user is currently enrolled in, they will still be listed under mycourses without categories.
• Show my course categories (navshowmycoursecategories) Default: No If enabled courses in the users my courses branch will be shown in categories.
• Link admin categories (linkadmincategories) Default: No If enabled admin setting categories will be displayed as links in the navigation and will lead to the admin category pages.

I'm creating this as a separate issue because the original is already in integration and needs to be closed asap.