Set Travis PYTHONPATH, clear ref to old Docker cache.
Set Travis PYTHONPATH, clear ref to old Docker cache.

faucetsdn/faucet,trungdtbk/faucet,shivarammysore/faucet,REANNZ/faucet,wackerly/faucet,trentindav/faucet,trentindav/faucet,gizmoguy/faucet,anarkiwi/faucet,byllyfish/faucet,faucetsdn/faucet,REANNZ/faucet,gizmoguy/faucet,byllyfish/faucet,mwutzke/faucet,wackerly/faucet,anarkiwi/faucet,trungdtbk/faucet,mwutzke/faucet,shivarammysore/faucet