[xml] xmlcatalog: fails to resolve docbookx.dtd on Debian/testing

[David Nebauer <davidnebauer switch com au>]

I've just discovered that the url 
http://oasis-open.org/docbook/xml/4.2/docbookx.dtd fails to resolve on 
my (stock) Debian/testing system:

------------------------------------------------------------------------------------------------- 

$ xmlcatalog /etc/xml/catalog 
http://oasis-open.org/docbook/xml/4.2/docbookx.dtd
No entry for SYSTEM http://oasis-open.org/docbook/xml/4.2/docbookx.dtd
No entry for URI http://oasis-open.org/docbook/xml/4.2/docbookx.dtd
------------------------------------------------------------------------------------------------- 


This is somewhat strange as I can manually trace through the catalog files:

/etc/xml/catalog (line 49):
<delegateSystem 
systemIdStartString="http://www.oasis-open.org/docbook/xml/""file:///etc/xml/docbook-xml.xml"/> 

.
.
/etc/xml/docbook-xml.xml (line 44):
<delegateSystem 
systemIdStartString="http://www.oasis-open.org/docbook/xml/4.2/""file:///usr/share/xml/docbook/schema/dtd/4.2/catalog.xml"/> 

.
.
/usr/share/xml/docbook/schema/dtd/4.2/catalog.xml (lines 30-31):
<system systemId="http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd";
      uri="docbookx.dtd"/>

I should point out that docbookx.dtd (and related files) are actually 
installed where they are supposed to be.

The public ID resolves correctly:
------------------------------------------------------------------------------------------------- 

$ xmlcatalog /etc/xml/catalog "-//OASIS//DTD DocBook XML V4.2//EN"
file:///usr/share/xml/docbook/schema/dtd/4.2/docbookx.dtd
------------------------------------------------------------------------------------------------- 


Is this known behaviour?

Regards,
David. catalog= catalog=