Also worth noting:  other projects need to combine hashes too.  Here's a 64-bit version of the highly regarded C++ Boost[1] library's hash_combine() function (I replaced its 32-bit int literal with "a random" 64-bit one):

    x ^= (Py_uhash_t)y + 0x94ae1875aa5647f1UL + (x << 6) + (x >> 2);

It's very cheap.  It also sucks horribly if used as the guts Python's tuple hash loop ;-)

This isn't a paradox.  Best I can tell, Python may be unique in trying _not_ to make all hashes "look random".  If you have only randomish hashes to combine, the Boost approach works fine.