Recursive replacement

Consider the following xml document:
<root><a><b><a/></b></a></root>
and 2 queries:

1)replace {fn:doc("test.xml")//a} with <new-node/>
2) for $p in fn:doc("test.xml")//a
   do replace {$p}
      with element "new-node" {$p/*}

Due to the Compatibility of Update Primitives table it follows that the
deletion of
The upper-most <a> node doesn't contradicts woth the update of the inner
<a>-node.
Could you please explain me, what is the result of these statements (or an
error should be raised)

Best Regards, 
Leonid Novak, 
Sedna DBMS Team,
www.modis.ispras.ru