modify travis

.travis.yml

@@ -5,7 +5,8 @@ go:
   - "1.12"
 
 env:
-  - GO111MODULE=on CONSUL_VERSION=0.9.2
+  - GO111MODULE=on
+  - CONSUL_VERSION=0.9.2
 
 before_install:
   - curl -sLo consul.zip https://releases.hashicorp.com/consul/${CONSUL_VERSION}/consul_${CONSUL_VERSION}_linux_amd64.zip
@@ -14,8 +15,9 @@ before_install:
   - mv consul ~/bin
   - export PATH="~/bin:$PATH"
 
+install: true
+
 script:
-  - env | grep GO111MODULE
   - go fmt ./... && [[ -z `git status -s` ]]
   - go mod vendor && go test ./... -coverprofile=coverage.txt -covermode=atomic