Undertow breaks some JSF apps

Undertow breaks some JSF apps. I haven't narrowed the problem down yet but I want to go ahead and post this JIRA because it is a blocker for AS8.

I'm attaching a small JSF project that demonstrates the problem. When you run the WAR with -c standalone-jbossweb.xml it works fine.

With Undertow it breaks. You are unable to navigate based on the return value of a MethodExpression.

Also, you get this warning:

12:17:30,572 WARNING [javax.enterprise.resource.webcontainer.jsf.context] (default task-1) JSF1091: No mime type could be found for file /index.xhtml.  To resolve this, add a mime-type mapping to the applications web.xml.