fix(@angular/cli): support empty index base href attribute

Author: clydin

Diff for: packages/@angular/cli/lib/base-href-webpack/base-href-webpack-plugin.ts

@@ -26,7 +26,7 @@ export class BaseHrefWebpackPlugin {
           } else {
             // Replace only href attribute if exists
             const modifiedBaseTag = baseTagMatches[0].replace(
-              /href="\S+"/i, `href="${this.options.baseHref}"`
+              /href="\S*?"/i, `href="${this.options.baseHref}"`
             );
             htmlPluginData.html = htmlPluginData.html.replace(baseTagRegex, modifiedBaseTag);
           }

Diff for: tests/e2e/tests/build/base-href.ts

@@ -1,6 +1,6 @@
-import {ng} from '../../utils/process';
-import {expectFileToMatch} from '../../utils/fs';
-import {updateJsonFile} from '../../utils/project';
+import { ng } from '../../utils/process';
+import { expectFileToMatch, replaceInFile } from '../../utils/fs';
+import { updateJsonFile } from '../../utils/project';
 
 
 export default function() {
@@ -12,4 +12,7 @@ export default function() {
     }))
     .then(() => ng('build'))
     .then(() => expectFileToMatch('dist/index.html', /<base href="\/myUrl">/))
+    .then(() => replaceInFile('src/index.html', 'href="/"', 'href=""'))
+    .then(() => ng('build'))
+    .then(() => expectFileToMatch('dist/index.html', /<base href="\/myUrl">/));
 }