Malformed subcategory links in category list and blog articles

[billtomczak]

Steps to reproduce the issue

1. Create a category
2. Create a sub-category to that category
3. Create a Category Listing view and configure so sub-category link is created on the page

Expected result

A link something like www.example.com/category-menu/2-subcategory

Actual result

www.example.com/category-menu/2-subcategory?layout=

System information (as much as possible)

This started happening in Joomla 3.8.7 and has been confirmed not to occur in 3.8.6

Additional comments

This problem doesn't occur on category blog views. But the back-link to the subcategory in an article does end up with the empty layout variable.

[joomla-cms-bot]

Set to "closed" on behalf of @Quy by The JTracker Application at issues.joomla.org/joomla-cms/20292

[Quy]

Reported, fixed in #20229 and will be included in v3.8.8.

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