van.testing version 3.0.0-0ubuntu1 failed to build in oneiric

van.testing version 3.0.0-0ubuntu1 failed to build in oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110816/+build/2714183

Details about the rebuild:
http://people.ubuntuwire.org/~wgrant/rebuild-ftbfs-test/test-rebuild-20110816-oneiric.html

Direct link to the build log: https://launchpad.net/ubuntu/+archive/test-rebuild-20110816/+build/2714183/+files/buildlog_ubuntu-oneiric-i386.van.testing_3.0.0-0ubuntu1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 528 lines into the build log:

dpkg-source: info: upstream files that have been modified:
 van.testing-3.0.0/van.testing.egg-info/SOURCES.txt
dpkg-buildpackage: export CFLAGS from dpkg-buildflags (origin: vendor): -g -O2
dpkg-buildpackage: export CPPFLAGS from dpkg-buildflags (origin: vendor):
dpkg-buildpackage: export CXXFLAGS from dpkg-buildflags (origin: vendor): -g -O2
dpkg-buildpackage: export FFLAGS from dpkg-buildflags (origin: vendor): -g -O2
dpkg-buildpackage: export LDFLAGS from dpkg-buildflags (origin: vendor): -Wl,-Bsymbolic-functions
dpkg-buildpackage: source package van.testing
dpkg-buildpackage: source version 3.0.0-0ubuntu1
 dpkg-source --before-build van.testing-3.0.0
dpkg-buildpackage: host architecture i386
 /usr/bin/fakeroot debian/rules clean
debian/rules:7: /usr/share/cdbs/1/rules/langpack.mk: No such file or directory
make: *** No rule to make target `/usr/share/cdbs/1/rules/langpack.mk'. Stop.
dpkg-buildpackage: error: /usr/bin/fakeroot debian/rules clean gave error exit status 2
******************************************************************************
Build finished at 20110827-1823
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/van.testing-3.0.0