the way the RDFa export converts URIs from absolute to relative is broken.

it used to work in OOo 3.2, but relied on the base URI for the document being
stored being the same as the base URI of the loaded document, which led to other
problems and was thus fixed for OOo 3.2.1 by mav.

now the base URI on saveAs is the URI of the target document, and is thus
different from the URI of the loaded document.

this leads to wrong relative URIs in RDFa attributes:
document-internal URIs  point into the loaded document, not the target document.

the complex test in sfx2 breaks because of this problem.

apparently the relative/absolute URI infrastructure in xmloff doesn't really
work for document-internal URIs anyway.