problems with the release web repo

Hi,
I am getting this error:

$ make html
XML_CATALOG_FILES="catalog.xml " xsltproc --timing --xinclude --stringparam 
collect.xref.targets "only" --stringparam targets.filename "man.tdb" pile.xsl 
clisp.xml
Parsing stylesheet pile.xsl took 0 ms
warning: failed to load external entity 
"http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"
compilation error: file pile.xsl line 3 element import
xsl:import : unable to load 
http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl
make: *** [man.tdb] Error 5

this used to work relatively recently (a week ago?)
what happened?
thanks.

Sam.