On a jenkins node that has 1 executor that is trying to execute an upstream job via the "trigger/call builds on other projects" build step, the job hangs indefinately or until the user-supplied timeout is reached.

In the console for the main job, it shows:

Waiting for the completion of <name-of-upstream-project>

While the Jenkins dashboard shows the upstream project is trying to build, with the text:
(pending - Waiting for next available executor )

I would expect that the plugin would somehow be able to indicate to the jenkins node that only 1 executor is required.