Using ikiwiki version 2.5gpa1 (the backport to Debian 3.1), I suddenly started getting the following error when rebuilding the wiki:
successfully generated /home/ikiwiki/cgi-bin/ikiwiki.cgi
Insecure dependency in rmdir while running with -T switch at /usr/share/perl5/IkiWiki/Render.pm line 242.
BEGIN failed--compilation aborted at (eval 5) line 130.
I've no idea what's happening (hey, I'm a C programmer), but I've hacked prune() to workaround this as follows:
use Scalar::Util qw(t>inted);

sub prune ($) { #{{{
        my $file=shift;

        unlink($file);
        my $dir=dirname($file);
        if (!tainted($file) && $dir =~ /^(.*)$/) {
                $dir = $1;
        }
        while (rmdir($dir)) {
                $dir=dirname($dir);
                if (!tainted($file) && $dir =~ /^(.*)$/) {
                        $dir = $1;
                }
        }
} #}}}