I noticed in 1.636 and 1.638 that Jenkins nows puts the workspace in the job directory.

This is a major change. Do we really want it to work like that? This will force use of custom workspace everywhere because I don't think many will want workspace in the job directory.

So for example my Jenkins home is /opt/jenkins/

In the old days Jenkins would create the workspace as still documented https://wiki.jenkins-ci.org/display/JENKINS/Administering+Jenkins

So a job 'test' would create workspace /opt/jenkins/workspace/test

New style is /opt/jenkins/jobs/test/workspace

So the workspace is put in the jobs directory. Obviously the wrong location but default now.