The parent build of a matrix job executes the "Source Code Management" (eg: Subversion checkout) and "Build environment" (eg: Workspace Cleanup Plugin) sections of the job configuration.

I can't see where that would ever be useful (how would anything get access to the source code checkouts done by the parent build?) and is often detrimental (see https://issues.jenkins-ci.org/browse/JENKINS-16521) so maybe this issue is just to stop any build steps happening on the parent job?

However, assuming these steps do have some use for some users, can we please have a config option on the job that, when checked, prevents pre-build steps from being executed by parent builds of matrix jobs?