Now if I capitalize the name to "Atom", odd thing happens

Running hugo server:

- Initially the atom feed gets generated with empty content, as if
  .Content were "".
- But if I modify and save the index.atom.xml *while* the server is
  running, the content gets inserted fine.

Running hugo:

- Here, as there is no chance to regenerate like in the server case, the atom
  feed will always have empty content.

All of that just because I upper-cased the outputformat name?