In docker-custom-build-environnment-plugin 1.6.5-SNAPSHOT, I have this issue :
Your project is missing a Dockerfile
But I haven' in 1.6.4 release version.
In fact this is due to this PR : https://github.com/jenkinsci/docker-custom-build-environment-plugin/pull/37
I have tested without, and it's works.
I think that the test is too early in the process, maybe only with slave? Or only with gerrit-trigger-plugin? Or maybe the control will not be the same at this place?
I will continue my test and maybe propose a new PR to fix this.