Nested enums don't have a python object created

[joeshaw]

If you next an enum inside an object, like so:

message Foo {
    message Bar {
        enum Quux {
            NAH = 0;
            YEAH = 1;
         }

         optional Quux quux = 1;
    }

    optional Bar bar = 1;
}

It never is placed into the enums list, and the Python object is never constructed for it.