make sure the symlink with the old name "ispconfig.vhost" is removed before...

make sure the symlink with the old name "ispconfig.vhost" is removed before the new one with the name 000-ispconfig.vhost is created.

install/lib/installer_base.lib.php

@@ -837,6 +837,7 @@ class installer_base {
 		//copy('tpl/apache_ispconfig.vhost.master', "$vhost_conf_dir/ispconfig.vhost");
 		//* and create the symlink
 		if($this->install_ispconfig_interface == true) {
+			if(!@is_link("$vhost_conf_enabled_dir/ispconfig.vhost")) unlink("$vhost_conf_enabled_dir/ispconfig.vhost");
 			if(!@is_link("$vhost_conf_enabled_dir/000-ispconfig.vhost")) {
 				exec("ln -s $vhost_conf_dir/ispconfig.vhost $vhost_conf_enabled_dir/000-ispconfig.vhost");
 			}