The UI doesn't update when only showing issues (`split-issue-pr-search-results`)

1. Visit https://github.com/search?q=refined+github&type=Issues
2. Click Pull requests (and wait for load)
2. Click Issues

The UI isn't updated to reflect that now **only issues** are being shown. As you can see in the gif, the bug only appears _after_ seeing the Pull Requests:

![gif](https://user-images.githubusercontent.com/1402241/102154270-01e02900-3e47-11eb-82c2-d5d432a463c3.gif)