When two or more input documents are supplied in the
form of DOMSource objects (for example, by returning a
DOMSource in response to the doc() or document()
function when using a URIResolver) then the nodes in
two different documents do not necessarily have
distinct identity. This means that identity-sensitive
operations such as union and generate-id() and the "is"
operator may give incorrect results when operating on a
sequence of nodes that spans documents.
Source code fixed. Test case in users/rodgers (not
integrated into test suite). Applies to 8.0 and all
known previous releases.