Cannot filter issues by labels ending with a plus char in board view

Summary

When an issue label ends with a "+" ("plus") character, filtering by it will not work in the board view.

Steps to reproduce

• Create a new label and name it bug+
• Tag an issue with this label
• Switch to "Issue->Boards" and click on the search box. Add a label filter and select the bug+ label.
• Don't add anything else and hit enter.

What is the current bug behavior?

The view returns 0 results.

What is the expected correct behavior?

The view should return all issues with that label. It actually works in list view.

Relevant screenshots

Board view

List view

This bug happens on GitLab.com