There are times when it is useful to test changes on the Windows XP and 2003 VMs, but the direct use of functions not on those platforms makes this impossible.
Once applied, the kernel32 tests will run on the Windows XP and 2003 testbot VMs.
We have decided to no longer care about XP/2003 results, precisely because the maintenance cost of keeping the tests running is bigger than the benefits of supporting obsolete platforms.
If there's a case where you need to investigate the XP/2003 behavior, I'd suggest extracting just that test to a separate exe.