Developers are allowed to push to protected branch

Summary

Developers are allowed to push to protected branch when permission of "allowed to push" set to maintainers

Steps to reproduce

Create a repository and add it to protected branch, then "allowed to push" set to maintainers.

What is the current bug behavior?

Developers are allowed to push to protected branch when permission of "allowed to push" set to maintainers

What is the expected correct behavior?

Developers are not suppose to be allowed to push to protected branch when permission of "allowed to push" set to maintainers

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:		
Current User:	git
Using RVM:	no
Ruby Version:	2.5.3p105
Gem Version:	2.7.6
Bundler Version:1.16.6
Rake Version:	12.3.2
Redis Version:	3.2.12
Git Version:	2.18.1
Sidekiq Version:5.2.5
Go Version:	unknown
GitLab information
Version:	11.8.1
Revision:	657d508
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	postgresql
URL:		https://.com
HTTP Clone URL:	https://com/some-group/some-project.git
SSH Clone URL:	git@g.com:some-group/some-project.git
Using LDAP:	yes
Using Omniauth:	yes
Omniauth Providers:
GitLab Shell
Version:	8.4.4
Repository storage paths:

• default: /var/opt/gitlab/git-data/repositories Hooks: /opt/gitlab/embedded/service/gi

Possible fixes