Group maintainer cannot add members

Summary

Hi,

according to the documentation a maintainer should be able to add members to a group. https://gitlab.inf.ethz.ch/help/user/permissions.md

Unfortunately only an owner is able to add a new member using the URL https://gitlab.example.com/groups/MYGROUP/-/group_members

I am running the latest version of Gitlab-Ce (11.1.0) with Omnibus installation.

Steps to reproduce

Create a user and add it to a group with permission "Maintainer" Login as that user and try to add a new member

What is the current bug behavior?

Cannot see form to add new member when logged in as a groups maintainer

What is the expected correct behavior?

Should see form to add new member when logged in as a groups maintainer

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         RedHatEnterpriseServer 7.5
Current User:   git
Using RVM:      no
Ruby Version:   2.4.4p296
Gem Version:    2.7.6
Bundler Version:1.16.2
Rake Version:   12.3.1
Redis Version:  3.2.11
Git Version:    2.17.1
Sidekiq Version:5.1.3
Go Version:     go1.9.4 linux/amd64
GitLab information
Version:        11.1.0
Revision:       35c387c
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     postgresql
URL:            https://gitlab.example.com
HTTP Clone URL: https://gitlab.example.com/some-group/some-project.git
SSH Clone URL:  git@gitlab.example.com:some-group/some-project.git
Using LDAP:     yes
Using Omniauth: yes
Omniauth Providers: google_oauth2, github
GitLab Shell
Version:        7.1.4
Repository storage paths:

• default: /local/home/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 >= 7.1.4 ? ... OK (7.1.4)
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
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
Reply by email is disabled in config/gitlab.yml

Checking LDAP ...
Server: ldapmain

LDAP authentication... Success
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
Redis version >= 2.8.0? ... yes

Ruby version >= 2.3.5 ? ... yes (2.4.4)

Git version >= 2.9.5 ? ... yes (2.17.1)