Sorting by weight resets labels filter

Summary

Sorting by weight resets labels filter.

Steps to reproduce

1. Open https://gitlab.com/gitlab-org/gitlab-ce/issues
2. Filter issues by any filter (e.g. ~bug).
3. Sort issues by weight.
4. Page will be reloaded with empty labels filter.

What is the current bug behavior?

Sorting by weight resets labels filter.

What is the expected correct behavior?

Issues should be sorted by weight and be filtered by labels.

Output of checks

This bug happens on GitLab.com

GitLab Enterprise Edition 9.0.2-ee 3ed6218