allow local sauce runs to have the same job id

Author: yyx990803

build/karma.sauce.config.js

@@ -73,7 +73,7 @@ module.exports = function (config) {
     sauceLabs: {
       testName: 'Vue.js unit tests',
       recordScreenshots: false,
-      build: process.env.CIRCLE_BUILD_NUM || Date.now()
+      build: process.env.CIRCLE_BUILD_NUM || process.env.SAUCE_BUILD_ID || Date.now()
     },
     // mobile emulators are really slow
     captureTimeout: 300000,