Bug parsing xhtml-strict schema

Xerces 2.6.0 reports an error in:

http://www.w3.org/2002/08/xhtml/xhtml1-strict.xsd

against this regex pattern (among others):

    <xs:restriction base="xs:string">
      <xs:pattern value="[-+]?(\d+|\d+(\.\d+)?%)"/>
    </xs:restriction>

Xerces is complaining about the - that begins [-+]. Yet XML Schema Part 
2 http://www.w3.org/TR/xmlschema-2/#nt-charRange specifically allows a - 
to begin a positive character group.
I'm surprised Xerces gets this wrong on such a public example. Is there 
a version where this is fixed?
If not, can someone point to where the code that checks this is so I can 
temporarily fix it myself? Thanks.
Bob