Invalid redirect URL when using an outbound rewrite rule using the UrLRewriteFilter

We get something like:

/xwikihttp://localhost:8080/xwiki/bin/...

This happens when the outbound rule modifies the context path. The reason is caused by some hack in XWikiAuthServiceImpl.stripContextPathFromURL() which tries to remove the context path to please the SecurityFilter framework we're using which seem to require relative URLs without context paths...

And the issue is that stripContextPathFromURL() doesn't take into account the possible effects of HttpServletResponse.encodeURL().