Can override pipeline by cancelling it

Summary

When running a CICD pipeline, if you cancel the pipeline, even when allowed_failure: false on jobs under pipeline, when: manual jobs can still be run:

Steps to reproduce

Create a new pipeline, create a manual task that is set to allowed_failure: false, then run the pipeline. Click into the pipeline and cancel before the first stage has been completed, see the MANUAL "PLAY" button ready for the second pipeline even though the first one has not succeeded.

Example Project

https://gitlab.com/rossrondeau/testing-failed-pipelines/pipelines/61318208

What is the current bug behavior?

It allows failed pipelines to be skipped

What is the expected correct behavior?

Should not be allowed to hit "play" on manual pipelines

Relevant logs and/or screenshots

https://gitlab.com/rossrondeau/testing-failed-pipelines/pipelines/61318208

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:env:info)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

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