Please describe the problem:
Relax NG validation in some cases fails when used with xmlReader API where it should not. It succeeds on the same input when using tree API.

The three RNG files below and a test XML file demonstrate the problem.

Steps to reproduce:
1. create files foo.rng, foo_1_1.rng, foo_1_2.rng and test.xml from the XML given int the "other information" section below
2. run 
  xmllint --noout --relaxng  foo.rng test.xml
and see
  test4.xml validates
3. run
  xmllint --noout --stream --relaxng  foo.rng test4.xml
and see
test4.xml:4: element foo: Relax-NG validity error : Element foo failed to validate attributes
test4.xml:4: element foo: Relax-NG validity error : Invalid attribute version for element foo
test4.xml fails to validate



Actual results:
3. fails while 2. succeedes 

Expected results:
both should succeed

Does this happen every time?
yes

Other information:
Versions: libxml2-2.6.31
   compiled with: Threads Tree Output Push Reader Patterns Writer SAXv1 FTP HTTP DTDValid HTML Legacy C14N Catalog XPath XPointer XInclude Iconv ISO8859X Unicode Regexps Automata Expr Schemas Schematron Modules Debug Zlib

rpm from openSuse 10.3 XML repository.

The input files:

============================
foo.rng

<?xml version="1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
	xmlns:s="http://foo.cz/">
  <start>
    <choice>
      <ref name="foo1.1"/>
      <ref name="foo1.2"/>
    </choice>
  </start>
  <define name="foo1.1">
    <externalRef href="foo_1_1.rng"/>
  </define>
  <define name="foo1.2">
    <externalRef href="foo_1_2.rng"/>
  </define>
</grammar>


======================
foo_1_1.rng

<?xml version="1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
	xmlns:s="http://foo.cz/">
  <start combine="choice">
    <ref name="foo.element"/>
  </start>

  <define name="version">
    <value>1.1</value>
  </define>

  <define name="foo.element">
    <element name="s:foo">
      <attribute name="version">
	<ref name="version"/>
      </attribute>
      <empty/>
    </element>
  </define>
</grammar>


======================
foo_1_2.rng

<?xml version="1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
	xmlns:s="http://foo.cz/">

  <include href="foo_1_1.rng">
    <define name="version">
      <value>1.2</value>
    </define>
  </include>

  <start>
    <ref name="foo.element"/>
  </start>


</grammar>

======================
test.xml

<?xml version="1.0" encoding="utf-8"?>
<foo
  xmlns="http://foo.cz/"
  version="1.1"/>