Quick command /relabel does not affect correct labels

Summary

The /relabel quick command correctly adds the new label, but removes the wrong label.

Steps to reproduce

1. Create issue with multiple labels. In my case, the issue had labels "Type: Feature" and "Status: Not Started".
2. Use the /relabel quick command in a comment to change status label: /relabel ~"Status: Not Started" ~"Status: In Progress".

Example Project

JoelFeiner/BugTest#1

This includes an issue showing the behavior.

What is the current bug behavior?

First label specified is not removed and another label, not at all specified in the command, is removed instead.

What is the expected correct behavior?

First label specified is removed and second label specified is added.

Relevant logs and/or screenshots

See link above.

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:		
Current User:	git
Using RVM:	no
Ruby Version:	2.3.5p376
Gem Version:	2.6.13
Bundler Version:1.13.7
Rake Version:	12.1.0
Redis Version:	3.2.5
Git Version:	2.13.5
Sidekiq Version:5.0.4
Go Version:	unknown
GitLab information
Version:	10.1.0
Revision:	5a695c4
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	postgresql
URL:		https://
HTTP Clone URL:	https:///some-group/some-project.git
SSH Clone URL:	git@:some-group/some-project.git
Using LDAP:	no
Using Omniauth:	no
GitLab Shell
Version:	5.9.3
Repository storage paths:

• default: /var/opt/gitlab/git-data/repositories Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks Git: /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab Shell ...
GitLab Shell version >= 5.9.3 ? ... OK (5.9.3)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:root, or git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
19/99 ... ok
20/101 ... ok
20/102 ... ok
20/103 ... ok
20/104 ... ok
20/105 ... ok
21/106 ... ok
21/108 ... ok
21/109 ... ok
21/110 ... ok
21/112 ... ok
21/114 ... ok
21/115 ... ok
21/117 ... ok
19/118 ... ok
21/119 ... ok
21/120 ... ok
21/121 ... ok
7/122 ... ok
21/123 ... ok
21/124 ... repository is empty
21/127 ... repository is empty
21/128 ... ok
21/129 ... repository is empty
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Sidekiq ...
Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Checking Reply by email ...
IMAP server credentials are correct? ... yes
Init.d configured correctly? ... skipped
MailRoom running? ... skipped
Checking Reply by email ... Finished
Checking LDAP ...
LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab ...
Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
19/99 ... yes
20/101 ... yes
20/102 ... yes
20/103 ... yes
20/104 ... yes
20/105 ... yes
21/106 ... yes
21/108 ... yes
21/109 ... yes
21/110 ... yes
21/112 ... yes
21/114 ... yes
21/115 ... yes
21/117 ... yes
19/118 ... yes
21/119 ... yes
21/120 ... yes
21/121 ... yes
7/122 ... yes
21/123 ... yes
21/124 ... yes
21/127 ... yes
21/128 ... yes
21/129 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.3 ? ... yes (2.3.5)
Git version >= 2.7.3 ? ... yes (2.13.5)
Git user has default SSH configuration? ... yes
Active users: ... 8
Checking GitLab ... Finished