[PATCH] backup.pl: Fix issue with University of Toulouse change

[Adolf Belka <adolf.belka@ipfire.org>]

- Some months ago University of Toulouse changed any lists with a different French and
   English name from being duplicate files to being a file plus a symlink.
- Doing a restore from a backup with symlinks into a system with only file names
   resulted in a symlink trying to be created when a file with the same name already
   existed causing a failure.
- This failure stopped the restore part way through resulting in only a partial restore.
- This patch removes all entries in the urlfilter blacklists, allowing all restored
   entries to be created.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
---
 config/backup/backup.pl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/config/backup/backup.pl b/config/backup/backup.pl
index 7454ae762..417d33f40 100644
--- a/config/backup/backup.pl
+++ b/config/backup/backup.pl
@@ -2,7 +2,7 @@
 ###############################################################################
 #                                                                             #
 # IPFire.org - A linux based firewall                                         #
-# Copyright (C) 2007-2025  IPFire Team  <info@ipfire.org>                     #
+# Copyright (C) 2007-2026  IPFire Team  <info@ipfire.org>                     #
 #                                                                             #
 # This program is free software: you can redistribute it and/or modify        #
 # it under the terms of the GNU General Public License as published by        #
@@ -83,6 +83,10 @@ restore_backup() {
 	# certificates being left in directory after a restore
 	rm -f /var/ipfire/ovpn/certs/*
 
+	# remove all previous blacklist entries from urlfilter
+	# to prevent any clashes between symlinks and files
+	rm -Rf /var/ipfire/urrlfilter/blacklists/*
+
 	# Extract backup
 	if ! tar xvzpf "${filename}" -C / \
 			--exclude-from="/var/ipfire/backup/exclude" \
-- 
2.54.0