In Jenkins 1.531 the behaviour is still as described by Erich.
What's even uglier is that when leaving the box ticked a workspace local repository will always be used, even if default and/or job settings specify a repository local to the executor. In my use case that results in (matrix-)builds that take a lot longer than they should.
It is not possible to configure executor-local repositories, except by turning off "use private repository" every time the job is modified and hard-coding -Dmaven.repo.local=$HOME/jenkins/maven-repositories/$EXECUTOR_NUMBER into the argument of the pre-build job.
Should the checkbox be removed (as per suggestions by radaczynski) I definitely would expect the pre/post jobs to use the same maven.repo.local configuration as the main job.