Issue board allows me to filter assignee and authors who are not relevant to me or my projects

Summary

While viewing the issue board, on filtering users in assignee and authors I am shown a list of users who I do not know.

I did try to search for this and did not find any duplicates hence filing. https://gitlab.com/gitlab-org/gitlab-ce/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=bug&search=assignee

Steps to reproduce

1. Sign up for gitlab
2. Create a new project, commit and push code
3. Go to the issue page, my link is https://gitlab.com/dashboard/issues?assignee_id=1607006
4. Filter on either Assignee or Author

What is the current bug behavior?

I am shown a list of users who I do not know and it seems like bogus users.

What is the expected correct behavior?

Given that I am a new user, I don't expect to be able to filter on assignees or users who I do not participate in a project with.

Relevant logs and/or screenshots

Upon investigating the backend REST API calls I am seeing the below.

On further investigation it appears that these users have emojis in their names

Request URL:https://gitlab.com/autocomplete/users.json?search=&per_page=20&active=true&project_id=&group_id=&skip_ldap=&todo_filter=&todo_state_filter=&current_user=true&author_id=&skip_users=
[  
   {  
      "id":1607006,
      "name":"Mek Stittri",
      "username":"mekdev",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/99ccce0dc0bb63df5034e1d2e067f8f7?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/mekdev",
      "path":"/mekdev"
   },
   {  
      "id":1733122,
      "name":"🐉",
      "username":"lz93ad",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/cf15b6480fae3743e742f84f4c94bc90?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/lz93ad",
      "path":"/lz93ad"
   },
   {  
      "id":1676054,
      "name":"🐙",
      "username":"zerocinque",
      "state":"active",
      "avatar_url":"https://assets.gitlab-static.net/uploads/-/system/user/avatar/1676054/avatar.png",
      "web_url":"https://gitlab.com/zerocinque",
      "path":"/zerocinque"
   },
   {  
      "id":511376,
      "name":"🐤",
      "username":"Plazmaz",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/dd8a3290d5e60726e045a04be569c178?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/Plazmaz",
      "path":"/Plazmaz"
   },
   {  
      "id":1927302,
      "name":"🐧",
      "username":"SilberRegen",
      "state":"active",
      "avatar_url":"https://assets.gitlab-static.net/uploads/-/system/user/avatar/1927302/avatar.png",
      "web_url":"https://gitlab.com/SilberRegen",
      "path":"/SilberRegen"
   },
   {  
      "id":232871,
      "name":"🐨",
      "username":"ricardod31",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/60fbc73841700d30076bdd7fdc53a8ae?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/ricardod31",
      "path":"/ricardod31"
   },
   {  
      "id":876913,
      "name":"🐵",
      "username":"dhanifudin",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/377df3379fcdea47446794bd47ed8076?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/dhanifudin",
      "path":"/dhanifudin"
   },
   {  
      "id":1406424,
      "name":"👀",
      "username":"moheb_magdy888",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/45b7bfadc928536cffd411171d846012?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/moheb_magdy888",
      "path":"/moheb_magdy888"
   },
   {  
      "id":1816595,
      "name":"👽",
      "username":"colgatto",
      "state":"active",
      "avatar_url":"https://assets.gitlab-static.net/uploads/-/system/user/avatar/1816595/avatar.png",
      "web_url":"https://gitlab.com/colgatto",
      "path":"/colgatto"
   },
   {  
      "id":1465937,
      "name":"😉",
      "username":"DeSoto",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/d4e2e5da2bf183779b1b1d7fb740bc9c?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/DeSoto",
      "path":"/DeSoto"
   },
   {  
      "id":1118905,
      "name":"😻",
      "username":"hazzdeath",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/a728e7d65453162e8da6ce9840697343?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/hazzdeath",
      "path":"/hazzdeath"
   },
   {  
      "id":1665323,
      "name":"🥀",
      "username":"jare5d",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/a20cc4b0904048202c4cccf8f418f095?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/jare5d",
      "path":"/jare5d"
   },
   {  
      "id":1363248,
      "name":"🦁",
      "username":"BrabblingBeard",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/838c386ee0e567f2f9bf56c53c4442ce?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/BrabblingBeard",
      "path":"/BrabblingBeard"
   },
   {  
      "id":153745,
      "name":"🦉",
      "username":"LestaD",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/dd475be8a2ad62d0b9f9440a1267bf4b?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/LestaD",
      "path":"/LestaD"
   },
   {  
      "id":1786690,
      "name":"👩🏾‍💻Code Black UMD👨🏿‍💻",
      "username":"codeblackUMD",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/b2acd698067104184608916c0c4c44c3?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/codeblackUMD",
      "path":"/codeblackUMD"
   },
   {  
      "id":1903958,
      "name":"🇦 🇱 🇮 🇨 🇪 🔄",
      "username":"asahina1979",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/415eb3c52a2766abafbfdd00ed0c70a7?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/asahina1979",
      "path":"/asahina1979"
   },
   {  
      "id":657846,
      "name":"🦄     Radiks   🦄",
      "username":"Radiks",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/8271e632faee6a836d7a4ebe435a3d2b?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/Radiks",
      "path":"/Radiks"
   },
   {  
      "id":331646,
      "name":"🙈  jacopo beschi 🙉",
      "username":"jacopo-beschi",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/692fb66988ac3863f360e846c1afc4f3?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/jacopo-beschi",
      "path":"/jacopo-beschi"
   },
   {  
      "id":689102,
      "name":"🤖 Amany EL Romeh  🤖",
      "username":"amanyelromeh",
      "state":"active",
      "avatar_url":"https://assets.gitlab-static.net/uploads/-/system/user/avatar/689102/avatar.png",
      "web_url":"https://gitlab.com/amanyelromeh",
      "path":"/amanyelromeh"
   },
   {  
      "id":206912,
      "name":"🤔 Anton",
      "username":"anton_07",
      "state":"active",
      "avatar_url":"https://secure.gravatar.com/avatar/97cb4c2f9bdfd3c9788736e5974a0cdb?s=80\u0026d=identicon",
      "web_url":"https://gitlab.com/anton_07",
      "path":"/anton_07"
   },
   {  
      "id":1847710,
      "name":"👕 Bařgain",
      "username":"bar9ain",
      "state":"active",
      "avatar_url":"https://assets.gitlab-static.net/uploads/-/system/user/avatar/1847710/avatar.png",
      "web_url":"https://gitlab.com/bar9ain",
      "path":"/bar9ain"
   }
]

Output of checks

This bug happens on GitLab.com

/label ~bug