Steps to Reproduce

1. Create a space
2. Change the space theme to the Documentation Theme
3. Create a page under the homepage of the space
4. Create another page under the page created in step #3
5. Navigate to the page created in step #3
6. Search for any terms in the left navigation panel's (Documentation Theme) Search Box

Notice that regardless of which page you are currently viewing, whether it's the page created in step #3, or the page created in step #4, the ancestorID appended to the search is always, the ancestorID of the space's homepage