After more testing, I did get a reproducable market crash. I think I have found the bug. When Stephane made the changes with the new "harvesting" code in Building, he made several changes where they where required related to the targetBuilding variable, but forgot to update line Unit.cpp:585, where targetBuilding is set to NULL, but does not execute the removeUnitFromHarvestingfunction in this new structure. I'm currently testing to see if this is a standard bug.
For future reference, release candidates are not the place to be putting new code. -- Extra cheese comes at a cost. Bradley Arsenault.