Expected behavior: Valid XML is presented, as per production: https://en.wikipedia.org/wiki/Special:Export/Main_Page (works)
Actual behaviour: XML Parsing error on beta: https://en.wikipedia.beta.wmflabs.org/wiki/Special:Export/Main_Page
XML Parsing Error: no root element found
Location: https://en.wikipedia.beta.wmflabs.org/wiki/Special:Export/Main_Page
Line Number 1, Column 1:
It yields a 0 byte output!