I believe this was a bug specific to the llvm-gcc compiler shipped with Xcode 4.1 and possibly Xcode 4.0.  I do not have Xcode 4 on OS X 10.6 but haypo's test does fail with the llvm-gcc 4.2.1 that comes with Xcode 4.1 on 10.7.  Can you confirm exactly which compiler you are using, i.e. the complete --version output from the compiler used in your python build?  If you have not installed Xcode 4.2, one solution is to use CC=gcc-4.2 which uses the plain gcc-4.2, not llvm-gcc-4.2.  For 10.6, I recommend sticking with Xcode 3 if at all possible for the time being.