espdiff prints wrong text when called with bad option

[cgedwards]

lsb_release -rd gives: Ubuntu 14.04.1 LTS

apt-cache policy patchutils gives:
patchutils:
  Installed: 0.3.2-3
  Candidate: 0.3.2-3
  Version table:
 *** 0.3.2-3 0
        500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status

Running espdiff --asdf outputs to stderr:

espdiff: unrecognised option '--asdf'
Try 'cat --help' for more information.

I would expect it to output to stderr:

espdiff: unrecognised option '--asdf'
Try 'espdiff --help' for more information.