Is tests.jvms calculated by junit, ant, or the ant config?

This question is specifically in the context of the build/test system for Lucene/Solr.

I can't find anything in the build.xml or any included configs that calculates tests.jvms when it is set to auto, so I must conclude that it is calculated either by junit or ant.  The former seems more likely, so here I am.
 

 When the number of CPU cores in the system is 4, tests.jvms is set to 3.  This seems like a reasonable choice to me, so no complaints there.  What I'd like to change is what happens when there are three CPU cores in the system -- an AMD X3 cpu.  I think tests.jvms should be set to 2 in that instance, but the automatic calculation sets it to 1.
 

 Which project gets the bug/wish issue - Lucene, Ant, or Junit?  Is my idea reasonable?

 

 Thanks,
 Shawn