vrb version 0.5.1-5 failed to build in oneiric

vrb version 0.5.1-5 failed to build in oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110816/+build/2714456

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/2714456/+files/buildlog_ubuntu-oneiric-amd64.vrb_0.5.1-5_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 424 lines into the build log:

ln -fs libvrb.so.0 lib/libvrb.so
mkdir -p bin
mkdir -p obj/bin/vbuf
gcc -pipe -O2 -DARCH_x86_64 -DARCH=x86_64 -DGENARCH_unknown -DGENARCH=unknown -DENDIAN2=10 -DENDIAN4=3210 -DENDIAN8=76543210 -DLIBC1999=1 -DLinux -DGNU -fomit-frame-pointer -funsigned-char -funsigned-bitfields -frerun-loop-opt -finline -finline-functions -Werror -Wall -Wnested-externs -Wno-cast-qual -Wno-trigraphs -Wuninitialized -Wwrite-strings -c -o obj/bin/vbuf/vbuf.o -I ../vrb/src/bin -I ../include -I- -I ./include ../vrb/src/bin/vbuf.c
cc1: note: obsolete option -I- used, please use -iquote instead
../vrb/src/bin/vbuf.c: In function 'main':
../vrb/src/bin/vbuf.c:429:11: error: variable 'poll_num' set but not used [-Werror=unused-but-set-variable]
cc1: all warnings being treated as errors

make[2]: *** [obj/bin/vbuf/vbuf.o] Error 1
make[2]: Leaving directory `/build/buildd/vrb-0.5.1/build'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/build/buildd/vrb-0.5.1'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110824-0406
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/vrb-0.5.1