hy: correct logic about skipping write
hy: correct logic about skipping write

- We do want to write maps, when they're not
  empty, but we don't want to write files which
  have no parents (i.e. the top-level object
  representing a directory, and nil maps).

opentable/sous,opentable/sous,opentable/sous,nyarly/sous,samsalisbury/sous,nyarly/sous,opentable/sous,samsalisbury/sous,samsalisbury/sous,samsalisbury/sous,samsalisbury/sous,opentable/sous,nyarly/sous