Do not rebuild users for 1.8.1 update

Author: jaapmarcus

install/upgrade/versions/1.8.1.sh

@@ -20,7 +20,7 @@
 upgrade_config_set_value 'UPGRADE_UPDATE_WEB_TEMPLATES' 'true'
 upgrade_config_set_value 'UPGRADE_UPDATE_DNS_TEMPLATES' 'false'
 upgrade_config_set_value 'UPGRADE_UPDATE_MAIL_TEMPLATES' 'true'
-upgrade_config_set_value 'UPGRADE_REBUILD_USERS' 'true'
+upgrade_config_set_value 'UPGRADE_REBUILD_USERS' 'false'
 upgrade_config_set_value 'UPGRADE_UPDATE_FILEMANAGER_CONFIG' 'false'
 
 if [ "$MAIL_SYSTEM" = "exim4" ]; then