jhbuild sanitycheck failing on Ubuntu 14.04 (Trusty)

Question

I'm trying to set up jhbuild on Ubuntu 14.04. When I run jhbuild sanitycheck, I get two messages:

Could not find DocBook XML DTD V4.1.2 in XML Catalog
Could not find DocBook XSL Stylesheets in XML Catalog

The code that checks this in jhbuild is

for (item, name) in [('-//OASIS//DTD DocBook XML V4.1.2//EN',
                                  'DocBook XML DTD V4.1.2'),
                                 ('http://docbook.sourceforge.net/release/xsl/current/html/chunk.xsl',
                                  'DocBook XSL Stylesheets')]:
                try:
                    data = get_output(['xmlcatalog', '/etc/xml/catalog', item])
                except:
                    print 'Could not find %s in XML catalog' % name   

and, sure enough, in /etc/xml/catlog, there are entries which almost, but not exactly, match what the code is looking for. Eg. a reference to -//OASIS//DTD DocBook XML (no version number) and http://docbook.sourceforge.net/release/xsl/ (without the current/html/chunk.xsl bit).

The official Ubuntu docbook-xml and docbook-xsl packages are installed.

It looks like the contents of /etc/xml/catalog aren't what jhbuild is expecting. 14.04 was installed from scratch; I've added a few other packages from various PPAs but can't think what could have changed this.

1. Anyone else experiencing this? (I'll see if it's the same on a fresh install on a VM)
2. What's the best way of fixing it - should I edit /etc/xml/catalog, change the jhbuild sanitycheck source (but would any other part of the system then break) or something else?