[pwg]

Fair enough, but then the "salt" is not really a "salt" anymore as that term is known from "password salt", because it is no longer a random input value unique to each different password. It is simply a piece of known-plaintext input for every "hashing" session.

That means that an attacker who can somehow obtain the salt value can now mount a known-plaintext attack against the outputs of the algorithm. http://en.wikipedia.org/wiki/Known-plaintext_attack

I am ignoring the fact that in a general sense an attacker with resources to obtain the salt can also likely log the master password, in which case no attack against the algorithm is necessary.