support publicPath auto

Author: AndreiSoroka

packages/@vue/cli-service/lib/commands/serve.js

@@ -116,9 +116,7 @@ module.exports = (api, options) => {
       protocol,
       host,
       port,
-      isAbsoluteUrl(options.publicPath) || options.publicPath === 'auto'
-        ? '/'
-        : options.publicPath
+      isAbsoluteUrl(process.env.BASE_URL) ? '/' : process.env.BASE_URL
     )
     const localUrlForBrowser = publicUrl || urls.localUrlForBrowser
 
@@ -189,7 +187,7 @@ module.exports = (api, options) => {
           'text/html',
           'application/xhtml+xml'
         ],
-        rewrites: genHistoryApiFallbackRewrites(options.publicPath, options.pages)
+        rewrites: genHistoryApiFallbackRewrites(process.env.BASE_URL, options.pages)
       },
       hot: !isProduction
     }, projectDevServerOptions, {

packages/@vue/cli-service/lib/util/resolveClientEnv.js

@@ -7,7 +7,7 @@ module.exports = function resolveClientEnv (options, raw) {
       env[key] = process.env[key]
     }
   })
-  env.BASE_URL = options.publicPath
+  env.BASE_URL = options.publicPath === 'auto' ? '' : options.publicPath
 
   if (raw) {
     return env