Knowledge Blocks affect categories visible on Knowledge Homepage

If the Knowledge Blocks plugin is enabled, when filtering for the categories on knowledge homepage displaying knowledge base articles, the knowledge blocks are not filtered out. 

Steps to Reproduce:

1. In a given knowledge base, such as Knowledge (OOB KB), make sure all articles have a Category (kb_category) set.
2. Navigate to the Knowledge Homepage and note that the Category of "(empty)" is not shown.
3. Install plugin Knowledge Blocks
4. Create a knowledge block without a Category (kb_category) and submit and publish it.
5. Navigate to the Knowledge Homepage and note that the Category of "(empty)" is shown.

Madrid

PRB1347723 "Knowledge blocks affect categories visible on the Knowledge homepage"

PRB1347723 is fixed in New York.