Magic Mania 1⅔: Fixes #4335

Fixes #4335

Readds the 1/12 chance of stumbling out the bolt of change fully human with no mutantrace. It must have gotten lost during the mutantrace datumizing
> should just be new pick((typesof(/datum/species) - /datum/species)

Need to store the result of pick to a var first.  Your example will look for a variable named 'pick' containing a path, and pass a list to the constructor.