They've also released code to generate an arbitrarily large number of colliding keys for MurmurHash2 and CityHash64, and one to recover the secret key of Python's randomized hash function. At some point here you're doing cryptography whether you want to or not -- and most of these randomized hash functions are just lousy cryptography.

This is right. My wording was incorrect, excuse me. I should have said more correctly "This is why the hashing functions used nowadays include a randomization with a seed determined at interpreter startup." Jruby for example now uses perls hashing algorithm. They used to rely on murmur2, just as cruby did.