Passing through non-defined CI variables assigns them a literal value instead of remaining empty
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=350747) </details> <!--IssueSummary end--> <!--- Please read this! Before opening a new issue, make sure to search for keywords in the issues filtered by the "regression" or "type::bug" label: - https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=regression - https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=type::bug and verify the issue you're about to submit isn't a duplicate. ---> ### Summary GitLab CI Variable with the same key and value is retained, so `URL: $URL` will have the value of `$URL` instead of it being empty. ### Steps to reproduce ```yaml stages: - test test-with-vars: stage: test variables: URL: $URL #same output NOTHING_TO_EXPAND: $VARIABLE_DOES_NOT_EXIST script: - echo $URL - echo $NOTHING_TO_EXPAND ``` ### Example Project <!-- If possible, please create an example project here on GitLab.com that exhibits the problematic behavior, and link to it here in the bug report. If you are using an older version of GitLab, this will also determine whether the bug is fixed in a more recent version. --> https://gitlab.com/gitlab-gold/faleksic-tests/public-group/ci-testing/-/tree/gitlab-ci-variable-issue Pipeline output: - https://gitlab.com/gitlab-gold/faleksic-tests/public-group/ci-testing/-/jobs/1997281173 ### What is the current *bug* behavior? <!-- Describe what actually happens. --> Instead of the value being empty because `$URL` is empty, the value of `URL` becomes `$URL`. ### What is the expected *correct* behavior? If key and value name are the same and the value is empty it should remain empty. ### Relevant logs and/or screenshots ![Screenshot_2022-01-20_at_4.24.25_PM](/uploads/74dee36bf6a7c39f50858d6e5e71e1e2/Screenshot_2022-01-20_at_4.24.25_PM.png) <!-- Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's tough to read otherwise. --> ### Output of checks <!-- If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com --> This bug happens on GitLab.com #### Results of GitLab environment info <!-- Input any relevant GitLab environment information if needed. --> <details> <summary>Expand for output related to GitLab environment info</summary> <pre> (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`) </pre> </details> #### Results of GitLab application Check <!-- Input any relevant GitLab application check information if needed. --> <details> <summary>Expand for output related to the GitLab application check</summary> <pre> (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) </pre> </details> ### Possible fixes <!-- If you can, link to the line of code that might be responsible for the problem. -->
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