The last paragraph of the section "Shallow Copy" says:

"" The base URI of a node is copied. However, if the copied node is subsequently
attached as a child to a new element, the final copy of the node inherits its
base URI from its parent node, unless this is overridden using an xml:base
attribute. ""

So it says only "as a child to a new element".  I guess document nodes be added
here too, because the same note occurs in all other node constructors.  For
example, xsl:element says:

"" Note, however, that this is only relevant when creating parentless elements.
When the new element is copied to form a child of an element or document node,
the base URI of the new copy is taken from that of its new parent. ""

Thanks to David Carlisle to help me finding this.

--drkm