Fix travis-ci config to only get vet when tip or later
Fix travis-ci config to only get vet when tip or later

helight/helight_code,helight/helight_code,helight/helight_code,cyflhn/go-zookeeper,rajivreddy/go-zookeeper,kmiku7/go-zookeeper-annotated,mikeqian/go-zookeeper,hailocab/go-zookeeper,figoxu/go-zookeeper,cch123/go-zookeeper,go-cloud/go-zookeeper,ngaut/go-zookeeper,lightpaw/go-zookeeper,helight/helight_code,wickman/go-zookeeper,mondough/go-zookeeper,ChannelMeter/go-zookeeper,tempbottle/go-zookeeper,theckman/go-zookeeper,helight/helight_code,aybabtme/go-zookeeper,helight/helight_code,dallasmarlow/go-zookeeper,helight/helight_code,helight/helight_code,zenoss/go-zookeeper,helight/helight_code