CI jobs following a stage with a manual step are running immediately

Summary

By default, jobs should only run if all jobs in the previous stage were successful. However, if the previous stage only contains a job with the when: manual directive, jobs in the subsequent stage run immediately, before completion or even commencement of the manual job . This appears to be a bug and is certainly new behaviour.

Steps to reproduce

.gitlab-ci.yml:

before_script:
  - echo "before_script"
  
stages:
 - Build
 - Test

Build:
  stage: Build
  script:
    - echo "Build"
  when: manual

Test:
  stage: Test
  script:
   - echo "Test"

Expected behavior

Job Test in stage Test should not start until job Build in stage Build is manually triggered and completes successfully.

Actual behavior

Job Test starts immediately.

Relevant logs and/or screenshots

Output of checks

Results of GitLab application Check

Checking GitLab Shell ...

GitLab Shell version >= 4.0.3 ? ... OK (4.0.3)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
4/3 ... ok
<cut>
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: OK
Send ping to redis server: 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 (omnibus-gitlab has no init script)
MailRoom running? ... can't check because of previous errors

Checking Reply by email ... Finished

Checking LDAP ...

Server: ldapprimary
LDAP authentication... Success
LDAP users with access to your GitLab server (only showing the first 100 results)
<cut>
Checking LDAP ... Finished

Checking GitLab ...

Git configured with autocrlf=input? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config outdated? ... no
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory setup correctly? ... 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: ...
4/3 ... yes
<cut>
Redis version >= 2.8.0? ... yes
Ruby version >= 2.1.0 ? ... yes (2.3.1)
Your git bin path is "/opt/gitlab/embedded/bin/git"
Git version >= 2.7.3 ? ... yes (2.7.4)
Active users: 17
Elasticsearch version 2.4.x? ... yes (2.4.2)
Elasticsearch has plugin delete-by-query installed? ... no

Checking GitLab ... Finished

Results of GitLab environment info


System information
System:         CentOS 7.2.1511
Current User:   git
Using RVM:      no
Ruby Version:   2.3.1p112
Gem Version:    2.6.6
Bundler Version:1.13.6
Rake Version:   10.5.0
Sidekiq Version:4.2.1

GitLab information
Version:        8.14.4-ee
Revision:       8c04d01
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     9.2.18
URL:            https://redacted
HTTP Clone URL: https://redacted/some-group/some-project.git
SSH Clone URL:  git@redacted:some-group/some-project.git
Elasticsearch:  yes
Geo:            no
Using LDAP:     yes
Using Omniauth: no

GitLab Shell
Version:        4.0.3
Repository storage paths:
- default:      /var/opt/gitlab/git-data/repositories
Hooks:          /opt/gitlab/embedded/service/gitlab-shell/hooks/
Git:            /opt/gitlab/embedded/bin/git

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)