Here are the steps to reproduce the bug:
1. Start with a clean Liferay installation with default config
2. Create a new blank site
3. Add a page with default settings to the new site
4. In Control Panel, go to new site's Documents and Media screen and add a new folder
5. Add a new document of type Contract inside the new folder. In my case the uploaded file was a Word document.
6. Go to the new site page and add a Web Content Display portlet to the page
7. Add a new web content by clicking the icon in the wcd portlet. Put some text in it and publish.
8. Edit the article you just created and in the article content, create a link to the document you added earlier. Publish the changes.
9. Go to the site's settings and activate local staging with defaults
10. Make a modification to the article (don't remove the link to the doc).
11. Try to publish to live so that in the publish form, select the current page and uncheck the following: bookmarks, calendar, mobile device rules, theme, logo.
13. When you click publish, you get the Manage Pages Temporarily unavailable message and a stacktrace in the log (see attachment)
I've debugged this a little bit, and it seems that the problematic code is in DLFileEntryPermission.java where on line 75 StagingPermissionUtil.hasPermission() is called.