[Soc2014] Official meta API

Note that: 1) You do not actually return  shallow copy here, despite this comment, 2) the `fields_map` method actually takes the result of this method and immediately mutates it, 3) That's not a problem whatsoever because `fields` is newly created in this method, no references to it are kept around, and this method isn't cached.

In short I think this comment can just be removed, there is no danger here whatsoever.