Leaf of type union containing identity-ref is not correctly transformed to XML

If some leaf has type union, which is containing also identity-ref, NormalizedNode with filled this leaf with some identity is not correctly rendered to XML.

E.g.:

module foo {
  namespace "foo-namespace";
  prefix "f";
  identity ident-base;
  identity ident-one {
    base ident-base;
  }

  ...
  leaf union-identityref-leaf {
    type union-type;
  }

  leaf identityref-leaf {
    type identityref {
      base ident-base;
    }

  }

  ...
}

If both leaves will have set as value identity ident-one, the XML converted output will be following:

<identityref-leaf>ident-one</identityref-leaf>
<union-identityref-leaf>(foo-namespace)ident-one</union-identityref-leaf>

The leaf identityref-leaf is converted correctly, but union-identityref-leaf with union has string QName included, which will not be converted using opposite direction.