[lxml] XInclude and xml:base

Hello, My document uses xi:include to include another XML document, and by default this adds an xml:base="common.xml" to the included node(s). Using xmllint --xinclude --nofixup-base-uris document.xml I can avoid adding xml:base. How can I achieve the same with lxml? I.e. how do I avoid the base? It seems that setting _Element.base to None is a poor, even unstable solution. Thanks! Jens -- Jens Tröger http://savage.light-speed.de/