allow go modules auto loading

Jenkinsfile

@@ -1,13 +1,13 @@
 /* Requires the Docker Pipeline plugin */
 /* Scripted pipeline */
-def enVars = '-e XDG_CACHE_HOME="/tmp" -e CGO_ENABLED=0 -e GOCACHE="/tmp/.cache"'
+def enVars = '-e XDG_CACHE_HOME="/tmp" -e CGO_ENABLED=0 -e GOCACHE="/tmp/.cache" -e GO111MODULE=auto'
 
 node {
     checkout scm
     stage('Build') {
         docker.image('golang').inside(enVars) {
-	    sh 'go version'
 	    sh 'mkdir -pv ${GOCACHE}'
+	    sh 'go version'
 	    sh 'go test -v -short'
         }
     }