Build 6509 does not have tsc drift bug?

Hello, it appears that windows 7 build 6509 from quick testing does not seem to suffer from this issue although 6519 has been claimed to have fixed this bug first.
i tried many reboots (i think i did it 20-30 times or more) and not one time has it failed unlike the known build before it (build 6498) where it once failed to start 1 service or it displayed a black screen upon boot or the setup just didnt launch.
maybe this information can help to narrow down where the drift bug fix first got implemented before other changes have occurred that may have muddied the waters in the code.
maybe its worthy to those that are still working on a solution. (win32ss and maybe some others)
please note that i have a haswell machine (i5 4460).