Timezone rake task outputs wrong timezone format

Summary

The timezones from gitlab-rake time:zones:all are pretty printed, indicating that the timezone in /etc/gitlab/gitlab.rb should be set with these timezones as-is.

Steps to reproduce

Following existing documentation: Changing your time zone

1. Run gitlab-rake time:zones:all or gitlab-rake time:zones[<two-letter-country-code>] (to get fewer results)
2. Copy timezone
3. Edit gitlab_rails['time_zone'] in /etc/gitlab/gitlab.rb to the timezone, like so:

gitlab_rails['time_zone'] = 'Pacific Time'

4. Run gitlab-ctl reconfigure

What is the current bug behavior?

After running the reconfigure, the setting will not be accepted

What is the expected correct behavior?

The timezone should be set correctly or the rake task should output the proper format.

Relevant logs and/or screenshots

There was an error running gitlab-ctl reconfigure:

execute[clear the gitlab-rails cache] (gitlab::gitlab-rails line 399) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
---- Begin output of /opt/gitlab/bin/gitlab-rake cache:clear ----
STDOUT:
STDERR: rake aborted!
ArgumentError: Invalid Timezone: Pacific Time
/opt/gitlab/embedded/service/gitlab-rails/config/initializers/time_zone.rb:1:in `<top (required)>'
/opt/gitlab/embedded/service/gitlab-rails/config/environment.rb:6:in `<top (required)>'
/opt/gitlab/embedded/bin/bundle:23:in `load'
/opt/gitlab/embedded/bin/bundle:23:in `<main>'

Caused by:
TZInfo::InvalidTimezoneIdentifier: Invalid identifier
/opt/gitlab/embedded/service/gitlab-rails/config/initializers/time_zone.rb:1:in `<top (required)>'
/opt/gitlab/embedded/service/gitlab-rails/config/environment.rb:6:in `<top (required)>'
/opt/gitlab/embedded/bin/bundle:23:in `load'
/opt/gitlab/embedded/bin/bundle:23:in `<main>'
Tasks: TOP => cache:clear => cache:clear:redis => environment
(See full trace by running task with --trace)
---- End output of /opt/gitlab/bin/gitlab-rake cache:clear ----
Ran /opt/gitlab/bin/gitlab-rake cache:clear returned 1

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

$ gitlab-rake gitlab:env:info
System information
System:		Ubuntu 16.04
Proxy:		no
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-ee
Revision:	39d0b2e
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	postgresql
DB Version:	9.6.11
URL:		http://gitlab.example.com
HTTP Clone URL:	http://gitlab.example.com/some-group/some-project.git
SSH Clone URL:	git@gitlab.example.com:some-group/some-project.git
Elasticsearch:	yes
Geo:		no
Using LDAP:	no
Using Omniauth:	yes
Omniauth Providers: gitlab
GitLab Shell
Version:	8.4.4
Repository storage paths:

• default: /mnt/gitlab/default/repositories
• storage1: /mnt/gitlab/storage1/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

$ gitlab-rake gitlab:check SANITIZE=true
Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 8.4.4 ? ... OK (8.4.4)
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 Gitaly ...
Gitaly: ... default ... OK
storage1 ... OK
Checking Gitaly ... Finished
Checking Sidekiq ...
Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Checking Incoming Email ...
Incoming Email: ... Reply by email is disabled in config/gitlab.yml
Checking Incoming Email ... Finished
Checking LDAP ...
LDAP: ... LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab App ...
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: ...
1/9 ... yes
1/10 ... yes
1/11 ... yes
1/12 ... yes
1/13 ... yes
1/14 ... yes
1/15 ... yes
1/16 ... yes
1/17 ... yes
1/18 ... yes
1/19 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.5 ? ... yes (2.5.3)
Git version >= 2.18.0 ? ... yes (2.18.1)
Git user has default SSH configuration? ... yes
Active users: ... 5
Elasticsearch version 5.6 - 6.x? ... yes (6.6.1)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes

Calling TZInfo::Timezone.all_identifiers in the rails console provides the proper format for timezones:

After adding gitlab_rails['time_zone'] = 'US/Pacific' to /etc/gitlab/gitlab.rb, the reconfigure is successful.