devhelp build fails

[Ian Martin <martin_id vodafone co nz>]

Hi,
I've just run into a build failure that I don't understand.  It's 
occurring on building documentation; I'm running Debian Sid and have 
just upgraded; the devhelp build is failing, with the following compile 
error:
#/usr/bin/xsltproc: relocation error: /usr/bin/xsltproc: symbol 
xsltMaxVars, version LIBXML2_1.0.24 not defined in file libxslt.so.1 
with link time reference.

I've reinstalled the xslt packages to make sure they're up to date.

I can get around it by simply omitting the devhelp file building, but 
that doesn't fix the underlying problem.  I suspect there's something 
very out of date in the /build/doc-reference makefile, as all the other 
packages built without this error.  Any suggestions where I should go 
looking?

Ian.