allow for links to nonexistent files in build environment to be added to package

(eval):3:in `link_without_potential_path_argument': No such file or directory - usr/local/bin/kt or /var/folders/9n/zpntlhcs6ls0qf_29ngjrhcr0000gn/T/package-dir-staging20130114-70813-gja6ry/usr/local/bin/kt (Errno::ENOENT)