magento2: Visibility is not respected by layered nav counts

Steps to reproduce

1. Have a category set up with layered navigation.
2. Set one of that category’s products visibility to “Search” (not visible on category directly).
3. Browse to the category
4. Filter the category by an attribute assigned to the product edited in step 2.

Expected result

1. Results count in pagination and layered navigation will match the number of products displayed.

Actual result

1. Results count will include products set to not visible on categories. The actual product list will not, creating a discrepancy.

Technical Info

I traced the issue back to \Magento\CatalogSearch\Model\ResourceModel\Fulltext\Collection::_renderFiltersBefore() (this is where $this->_totalRecords is set, from the search result). The search result returns 14 entity IDs matching the layered navigation criteria. The actual product list load ($this, in that class context) loads products in the category matching those results, with some other filters.

I took the product list collection query, added the entity_id results explicitly, and then picked out constraints to find the difference. Visibility was it: There are 5 set to visibility 4 (the number of actual results shown), and 9 set to 3 (search-only), for a total of 14 (the total results count shown above).

Best guess is that use of a search results object in the context of layered navigation is making Magento think ‘search!’ and ignore that it’s actually on a category.

Issue occurs on both 2.0.6 and 2.1.0.