ae4491b421
Fix error when CI job variables key used but not specified
## What does this MR do?
This MR fixes a an error when CI job variables specified, but not defined:
```yaml
image: ruby:2.2
test:
variables:
script:
- rspec
```
## What are the relevant issue numbers?
Closes #18764
Follow up discussion in: #18775
## Does this MR meet the acceptance criteria?
- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4745
|
||
|---|---|---|
| .. | ||
| api | ||
| assets | ||
| ansi2html.rb | ||
| charts.rb | ||
| gitlab_ci_yaml_processor.rb | ||
| model.rb | ||
| static_model.rb | ||
| version_info.rb | ||