🐛 Modify regex to allow subdir/ghost urls. (#8627)

no issue

- redirect admin url's if Ghost uses a subdirectory
- fixes a bug where reset password and invite links do not route to the right destination

core/server/admin/middleware.js

@@ -1,7 +1,10 @@
 var utils = require('../utils');
 
 function redirectAdminUrls(req, res, next) {
-    var ghostPathMatch = req.originalUrl.match(/^\/ghost\/(.+)$/);
+    var subdir = utils.url.getSubdir(),
+        ghostPathRegex = new RegExp('^' + subdir + '/ghost/(.+)'),
+        ghostPathMatch = req.originalUrl.match(ghostPathRegex);
+
     if (ghostPathMatch) {
         return res.redirect(utils.url.urlJoin(utils.url.urlFor('admin'), '#', ghostPathMatch[1]));
     }