Data URLs in CSS become blank after rewriting

[GoogleCodeExporter]

Here is an example:

Original URL in CSS:
url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABoAAAAaCAYAAACpSkzOAAACiklEQ�
��caHEKcNtwNMST+AskuNOG3FqWimaC9bEkZxfa/Y8IQYvwCF5eaw1/Gds0AAAAASUVORK5CYII=)

Rewritten URL in CSS:
url(http://parliamodivino.com/cache,_template,_modal-1eabe7a6.css+cache,_templa�
��qv==0.1+cache,_template,_template-28620727.css.pagespeed.cc.-FvUm2xruw.css)

Original issue reported on code.google.com by hui...@google.com on 15 Jan 2014 at 6:26