add check i18n en.json to the pipeline (#10557)

build/Jenkinsfile.pr

@@ -71,6 +71,25 @@ pipeline {
             }
         }
 
+        stage('Check i18n') {
+            environment {
+                GOPATH = "/go"
+            }
+
+            steps {
+                withDockerContainer(args: '-u root --privileged -v ${WORKSPACE}/src:/go/src/', image: 'mattermost/mattermost-build-server:feb-28-2019') {
+                    ansiColor('xterm') {
+                        sh """
+                            cd /go/src/github.com/mattermost/mattermost-server
+                            cp i18n/en.json /tmp/en.json
+                            make i18n-extract
+                            diff /tmp/en.json i18n/en.json
+                        """
+                    }
+                }
+            }
+        }
+
         stage('Build') {
             environment {
                 GOPATH = "/go"