NumberFormatException throw out from BufferUtil.java when run in GAE1.7.3+

I'm using richface 4.3.0.M2 and it's throwing the exception below when I run with GAE 1.7.3 and GAE 1.7.4. However, it works fine with GAE 1.7.2.

Any help or workarounds available?

INFO: request=com.google.appengine.tools.development.ResponseRewriterFilter$RequestWrapper@14e834c, response=com.google.appengine.tools.development.ResponseRewriterFilter$ResponseWrapper@18e2fc5, chain=Faces Servlet
14/12/2012 2:01:35 AM com.google.apphosting.utils.jetty.JettyLogger warn
WARNING: /javax.faces.resource/application.css.jsf
java.lang.NumberFormatException: Wed, 05 Dec 2012 23:22:19 GMT
    at org.mortbay.io.BufferUtil.toLong(BufferUtil.java:106)
    at org.mortbay.jetty.HttpFields$Field.getLongValue(HttpFields.java:1479)
    at org.mortbay.jetty.HttpFields.getLongField(HttpFields.java:720)
    at org.mortbay.jetty.Request.getIntHeader(Request.java:728)
    at javax.servlet.http.HttpServletRequestWrapper.getIntHeader(HttpServletRequestWrapper.java:106)
    at

Solution

I found out that it's a pending problem with google app engine. The issue page can be found here. They offer a workaround which does fix this problem, though it has not yet been fixed formally.