/usr/bin/moin-update-wikilist is in python-moinmoin 1.9.8-1+deb8u1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | #!/usr/bin/perl -t
# Add a user to the system wide wikilist.
# This script can safely be made suid.
use warnings;
use strict;
use English;
my $username=getpwuid($REAL_USER_ID);
if (! defined $username || ! length $username) {
	die "unable to determine user name for UID $REAL_USER_ID\n";
}
my $wikilist="/etc/moin/wikilist";
if (! -e $wikilist) {
	die "$wikilist does not exist\n";
}
my $removed=0;
my @lines;
open (my $list, "<$wikilist") || die "read $wikilist: $!";
while (<$list>) {
	chomp;
	if (/^\s*([^\s]+)\s*$/) {
		my $user=$1;
		if ($user eq $username) {
			$removed=1;		
		}
		else {
			push @lines, $_;
		}
	}
	else {
		push @lines, $_;
	}
}
close $list || die "error reading $list: $!";
open ($list, ">$wikilist") || die "write $wikilist: $!";
foreach (@lines) {
	print $list "$_\n";
}
if ($removed) {
	print "removed user $username from $wikilist\n";
}
else {
	print $list "$username\n";
	print "added user $username to $wikilist\n";
}
close $list || die "error writing $list: $!";
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