CI Job failing even on an almost empty script

GitLab CI/CD
1

I have cut down my CI job to the following:

    deploy_staging:
      type: deploy
      script:
        - echo "Test"
      only:
        - master

But even this is failing with the following:

Running with gitlab-runner 12.1.0 (de7731dd)
  on docker-auto-scale ed2dce3a
Using Docker executor with image ruby:2.5 ...
Pulling docker image ruby:2.5 ...
Using docker image sha256:9f5b0d20e8ecf42cd7b90c87721d5ee08c91c4480ff007341a7432d2c87300b6 for ruby:2.5 ...
Running on runner-ed2dce3a-project-13253656-concurrent-0 via runner-ed2dce3a-srm-1567161943-3bad0134...
/bin/bash: line 78: export: `1=_dwdawd__===': not a valid identifier
/bin/bash: line 78: export: `1=_dwdawd__===': not a valid identifier
ERROR: Job failed: exit code 1

Has anyone seen this before?