fix detection of renamed vlan interfaces

This fixes bug 327059, thanks to Jonathan for reporting this and for the patch.

net/vlan.sh

@@ -20,7 +20,7 @@ _is_vlan()
 _get_vlans()
 {
 	[ -e /proc/net/vlan/config ] || return 1
-	sed -n -e 's/^\(.*[0-9]\) \(.* \) .*'"${IFACE}"'$/\1/p' /proc/net/vlan/config
+	sed -n -e 's/^\W*\([^ ]*\) \(.* \) .*'"${IFACE}"'$/\1/p' /proc/net/vlan/config
 }
 
 _check_vlan()