CDPATH-related fix in safe-rm 0.7

Written for Safe-rm by François Marier on 2009-09-23

Version 0.7 of safe-rm fixes a small untainting problem for people who have CDPATH defined in their environment. Others can safely skip this release and stick to version 0.6.

Thanks to John Ferlito, who inadvertently deleted part of his /usr/lib (http://inodes.org/blog/2009/09/15/rm-rf-usrlib/), for this fix!