OK looks like a valid bug then. If you'd like to help, use the buildbot to pinpoint exactly when the game broke: http://buildbot.orphis.net/pcsx2/
Track the exact revision by using the binary search algorithm so you test the lowest possible builds to find it.
Let's say you have 1000 revs.You start at rev 500,test if the bug is there. If it's there, it means the bug was introduced before rev 500, so you test rev 250. If you get the bug, same thing etc etc.
If you test a build and the game works, you go the other way. So for example you test rev500 and it works. So the bug is between rev 500 and rev1000. Then you test rev 750 and so on and so forth
(you always choose min rev+max rev/2 to test, so 1000/2, 0+500/2, 250+500/2 etc )
So if the problematic rev was let's say rev 400 here is how it would go: Test rev 500->bugged. So the bug is between 0 and 500. Test rev 250->Works. So the bug is between 250 and 500. Test rev 375->Works. So the bug is between 375 and 500. Test rev437->Bugged. So the bug is between 375 and 437. See how we're closing up? Eventually you will get to rev 400