gitlab-runner does not find jobs from included files

Summary

Running jobs from included CI configuration files via gitlab-runner exec docker myjob does not work.

Steps to reproduce

See Example Project.

Example Project

See this simple Example. Both jobs run smoothly on gitlab CI. But only test-job-1 runs with gitlab-runner:

$ gitlab-runner exec docker test-job-1
[…]
$ echo Job 1
Job 1

$ gitlab-runner exec docker test-job-2
[…]
FATAL: no job named "test-job-2"

What is the current bug behavior?

Running included job via gitlab-runner leads to FATAL: no job named "myjob".

What is the expected correct behavior?

Running included job via gitlab-runner runs the job as it does for jobs that live in .gitlab-ci.yml directly.

Relevant logs and/or screenshots

See Example Project.

Output of checks

None

Results of GitLab environment info

$ gitlab-runner -v
Version:      12.7.1
Git revision: 003fe500
Git branch:   12-7-stable
GO version:   go1.13.5
Built:        2020-01-23T09:08:54+0000
OS/Arch:      linux/amd64

Results of GitLab application Check

None

Possible fixes

No idea.