rspec-all frontend_fixtures as-if-foss sometimes fails with CI_NODE_INDEX: unbound variable

Summary

The rspec-all frontend_fixtures as-if-foss pipeline job sometimes fails with the error:

/bin/bash: line 347: CI_NODE_INDEX: unbound variable

Note: I haven't seen it on master (yet?) so I'm using the bug template instead of the master broken template. Feel free to update.

Steps to reproduce

1. Create a branch that contains frontend changes and runs with the as-if-foss setting.
2. Create an MR for this branch.
3. Trigger a pipeline.

Example Project

gitlab-org/gitlab

What is the current bug behavior?

The CI job rspec-all frontend_fixtures as-if-foss fails.

What is the expected correct behavior?

The CI job rspec-all frontend_fixtures as-if-foss passes.

Relevant logs and/or screenshots

Observed failures:

• https://gitlab.com/gitlab-org/gitlab/-/jobs/4121894757 (!117082 (merged))
• https://gitlab.com/gitlab-org/gitlab/-/jobs/4122521152 (!117093 (merged))
• !117731 (merged)
• !117082 (merged)
• !117335 (merged)
• !117745 (merged)

Observed succeses:

• https://gitlab.com/gitlab-org/gitlab/-/jobs/4127492179 (!117082 (merged))
• https://gitlab.com/gitlab-org/gitlab/-/jobs/4123011486 (!117093 (merged))

Output of checks

Possible fixes