Fix __str__ when mask is None
Fix __str__ when mask is None

trungdtbk/faucet,gizmoguy/faucet,shivarammysore/faucet,mwutzke/faucet,faucetsdn/faucet,anarkiwi/faucet,shivarammysore/faucet,mwutzke/faucet,anarkiwi/faucet,REANNZ/faucet,faucetsdn/faucet,gizmoguy/faucet,REANNZ/faucet,trungdtbk/faucet