Automatically remove repeated labels in issue search bar

Resources

PM @victorwu | UX @cperessini | FE @alfredo1

Description

• Repeated labels are removed in the search bar when you hit enter. For example:
• Suppose a user types this in the search bar: label:~UX label:~UX
• The user hits enter to search.
• The page is refreshed and the search bar is updated to: label:~UX
• The search results are according to label:~UX

Stretch goal

• Do the same thing for other filters, i.e. author, milestone, and weight.

Case sensitivity

• Labels are case sensitive in GitLab, so label:~UX label:~Ux are two different labels and do not apply to this issue.

Problem

A user suggested this was a bug [Clip 1] (https://youtu.be/UF_zfCYgukw?t=5m36s).