Cannot deploy XWiki as ROOT application

This is a regression introduced in rev. 7272 (see http://fisheye2.cenqua.com/browse/xwiki/xwiki-platform/core/trunk/xwiki-core/src/main/java/com/xpn/xwiki/web/XWikiServletURLFactory.java?r1=6355&r2=7272), which causes links created by the XWikiServletURLFactory to have an extra /bin.

Thanks to Cristian Vrabie for reporting it.