gnustep-gui version 0.20.0-1ubuntu1 failed to build in oneiric

gnustep-gui version 0.20.0-1ubuntu1 failed to build in oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110816/+build/2694733

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/2694733/+files/buildlog_ubuntu-oneiric-amd64.gnustep-gui_0.20.0-1ubuntu1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1447 lines into the build log:

say.m: In function 'main':
say.m:17:12: error: variable 'outFile' set but not used [-Werror=unused-but-set-variable]
cc1obj: all warnings being treated as errors

make[6]: *** [obj/say.obj/say.m.o] Error 1
make[5]: *** [internal-tool-all_] Error 2
make[4]: *** [say.all.tool.variables] Error 2
make[3]: *** [internal-all] Error 2
make[3]: Leaving directory `/build/buildd/gnustep-gui-0.20.0/Tools/say'
make[2]: *** [internal-all] Error 2
make[2]: Leaving directory `/build/buildd/gnustep-gui-0.20.0/Tools'
make[1]: *** [internal-all] Error 2
make[1]: Leaving directory `/build/buildd/gnustep-gui-0.20.0'
make: *** [debian/build-shared-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110821-0154
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/gnustep-gui-0.20.0