Issue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. Create a pull request
2. In the pull request's diff tab, enter something in the "Filter file tree" or "Search changes" input filter
3. Update the pull request in another tab, such as by:
   1. editing description or title
   2. adding/removing a reviewer

Expected Results

The results returned by the filter in step 2 are still displayed.

Actual Results

The filter in step 2 is cleared (after a few seconds, depending on when the FE makes the next polling request), meaning the diff search results are gone, and the pull request diff now shows all files.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available