When reloading a page with an IFrame portlet configured with form authentication, a nested liferay page is loaded inside the IFrame.
Steps to reproduce
1. Add IFrame to the new page.
2. Configure portlet and set Source URL to: http://www.baidu.com
3. Enable Form authentication (Using default value)
4. Save and close configuration screen.
5. Note that the contents of the IFrame are displayed correctly. Please refer to ok.png.
6. Reload the page (might need to reload 8-10 times so that the url is enough long).
7. Note that a liferay page is showed nested (not_ok.png)