Comments are removed from config.toml

Summary

Comments in config.toml are removed when register/unregister a runner

Steps to reproduce

Edit config.toml add a comment

# Comment that should be here
concurrent = 2
check_interval = 0
# Another comment

[[runners]]
  name = "nameOfRunner"
  url = "https://gitlab.example.com/ci"
  token = "xxxxxxxxxxxxx"
  executor = "shell"
  [runners.cache]

Unregister a runner gitlab-runner unregister --name nameOfRunner

View config.toml

concurrent = 2
check_interval = 0

Actual behavior

Comments are removed

Expected behavior

Comments should not be removed in config.toml

Relevant logs and/or screenshots

Environment description

This is a on premise install of gitlab and using a shell executor

Used GitLab Runner version

$ gitlab-runner --version
Version:      9.5.0
Git revision: 413da38
Git branch:   9-5-stable
GO version:   go1.8.3
Built:        Tue, 22 Aug 2017 13:35:13 +0000
OS/Arch:      linux/amd64