fn:parse-xml-fragment does not raise err:FODC0006 when it should

[Sorin Marian Nasoi]

The test-cases "parse-xml-fragment-016", "parse-xml-fragment-017" and "parse-xml-fragment-020" from "fn-parse-xml-fragment" fail because of mishandling of err:FODC0006.

From the http://www.w3.org/TR/xpath-functions-30/#func-parse-xml-fragment:
"A dynamic error is raised [err:FODC0006] if the content of $arg is not a well-formed external general parsed entity, if it contains entity references other than references to predefined entities, or if a document that incorporates this well-formed parsed entity would not be namespace-well-formed."