Quoting :doc note-6-5:

  (SBCL only) The function [setenv$] is now supported in SBCL, which
  had been the one supported host Lisp for which setenv$ had not been
  supported. Thanks to Jared Davis for pointing the way to this
  improvement.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1267 5d84a466-a78b-0930-a311-59b22171a541