[xmlsec] Xml exclusive c14n

[Alex Boese]

I was noticing that exclusive canonicalization seems to differ between the lxml and xmlsec implementations. In my observations, if I exclusive c14n an entire xml document utilizing the lxml, namespaces that are unused are completely dropped. With xmlsec, if I do the same, they remain. 

By unused, I'm meaning a namespace with prefix that has no matching prefixed tags in children tags.

Is this deliberate behavior? If so, why the difference?

-Alex