Environment variable meanings have changed from release 1.1.13.

  The meanings of the environment variables PAPERSIZE and PAPERCONF
  have been reversed.  Previously, PAPERCONF specified a paper size
  (such as "letter" or "a4") and PAPERSIZE specified a path to a file
  from which to read the system's default paper size.  These
  environment variables now have the following meanings:

   PAPERSIZE: the paper size to be used
   PAPERCONF: the path to a configuration file to read for the paper size

  To maintain backward compatibilty, both variables fall back to their
  previous behaviour if their values are inconsistent with the new
  definitions.  However, this behaviour will change after the next
  Debian release, so you should take steps now to ensure that the
  system's custom scripts, cron jobs, and so forth use the new
  meanings.