Run CI pipeline without a merge request

[Dan Eble]

Is there a way to run a CI pipeline on a branch without creating a merge 
request first?  It seems that some people are outsourcing their development 
testing to GitLab, which I don't mind per se, but when there is an MR attached 
to the branch, the pushes generate email noise.

GitLab provides instructions[1] that sound simple.  When I tried following them 
with an old branch I just rebased, I got the message

    The form contains the following error:
        • No stages / jobs for this pipeline.

Maybe there are environment variables unknown to me which I am supposed to set.

Regards,
— 
Dan

[1] https://docs.gitlab.com/ee/ci/pipelines/#run-a-pipeline-manually