I believe python is fully at mercy of underlying system math library.

And as a matter of fact, this C program

#include <math.h>
#include <stdio.h>
main() { printf("%.6f\n", sin(1e22)); }

when compiled as 64-bit app (on linux) produces "-0.852201", but when it's compiled as a 32-bit app on the same machine (gcc -m32), it produces "0.462613".

So I don't think this is a bug in python.