Collapse sidebar not working

Summary

The collapsed sidebar broke, it won't collapse.

Steps to reproduce

This started happening in gitlab.com since ~15:00 CET . It's reproducible both on Chrome and Firefox, logged in and out.

What is the current bug behavior?

Sidebar used to collapse into a single column of icons.

What is the expected correct behavior?

The selected group is still displayed after collapsing the sidebar, blocking it from collapsing correctly.

Relevant logs and/or screenshots