mailfilter version 0.8.2-1 failed to build on amd64 with GCC-4.6/oneiric

mailfilter version 0.8.2-1 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461566

Details about the rebuild:
https://lists.ubuntu.com/archives/ubuntu-devel/2011-April/033042.html

Direct link to the build log: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461566/+files/buildlog_ubuntu-natty-amd64.mailfilter_0.8.2-1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 500 lines into the build log:

mv -f .deps/header.Tpo .deps/header.Po
g++ -DHAVE_CONFIG_H -I. -I.. -I/usr/include -I. -I../include -I.. -DLOCALEDIR=\"/usr/share/locale\" -I../intl -I.. -I../include -I. -Wall -g -O2 -MT weeder.o -MD -MP -MF .deps/weeder.Tpo -c -o weeder.o weeder.cc
mv -f .deps/weeder.Tpo .deps/weeder.Po
g++ -DHAVE_CONFIG_H -I. -I.. -I/usr/include -I. -I../include -I.. -DLOCALEDIR=\"/usr/share/locale\" -I../intl -I.. -I../include -I. -Wall -g -O2 -MT preferences.o -MD -MP -MF .deps/preferences.Tpo -c -o preferences.o preferences.cc
preferences.cc: In member function 'void Preferences::init()':
preferences.cc:85:53: error: using temporary as lvalue [-fpermissive]
preferences.cc:86:53: error: using temporary as lvalue [-fpermissive]
make[3]: *** [preferences.o] Error 1
make[3]: Leaving directory `/build/buildd/mailfilter-0.8.2/src'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/build/buildd/mailfilter-0.8.2'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/build/buildd/mailfilter-0.8.2'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110424-1416
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/mailfilter-0.8.2