This is a semi-automatic report based on the latest archive rebuild results [1].
Apologies if it reaches you in error.
Excerpt from the buildlog:
i686-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I. -I.. -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -D_FORTIFY_SOURCE=2 -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -MT transfer_mult.lo -MD -MP -MF .deps/transfer_mult.Tpo -c transfer_mult.cc -fPIC -DPIC -o .libs/transfer_mult.o
i686-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I. -I.. -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -D_FORTIFY_SOURCE=2 -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -MT transfer_mult.lo -MD -MP -MF .deps/transfer_mult.Tpo -c transfer_mult.cc -o transfer_mult.o >/dev/null 2>&1
if /bin/bash ../libtool --tag=CXX --mode=compile i686-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I. -I.. -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -D_FORTIFY_SOURCE=2 -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -MT tmx_builder.lo -MD -MP -MF ".deps/tmx_builder.Tpo" -c -o tmx_builder.lo tmx_builder.cc; \
then mv -f ".deps/tmx_builder.Tpo" ".deps/tmx_builder.Plo"; else rm -f ".deps/tmx_builder.Tpo"; exit 1; fi
i686-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I. -I.. -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -D_FORTIFY_SOURCE=2 -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -MT tmx_builder.lo -MD -MP -MF .deps/tmx_builder.Tpo -c tmx_builder.cc -fPIC -DPIC -o .libs/tmx_builder.o
i686-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I. -I.. -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -D_FORTIFY_SOURCE=2 -I/usr/include/libxml2 -I/usr/include/lttoolbox-3.1 -I/usr/lib/lttoolbox-3.1/include -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -MT tmx_builder.lo -MD -MP -MF .deps/tmx_builder.Tpo -c tmx_builder.cc -o tmx_builder.o >/dev/null 2>&1
/bin/bash ../libtool --tag=CXX --mode=link i686-linux-gnu-g++ -Wall -g -O0 -Wall -ansi -march=i686 -O3 -fomit-frame-pointer -funroll-loops -Wl,-Bsymbolic-functions -Wl,-z,relro -o libapertium3.la -rpath /usr/lib -version-info 0:0:0 -release 3.1 collection.lo constant_manager.lo hmm.lo interchunk.lo interchunk_word.lo lextor.lo lextor_data.lo lextor_eval.lo lextor_word.lo morpho_stream.lo postchunk.lo string_utils.lo tagger.lo tagger_data.lo tagger_utils.lo tagger_word.lo transfer.lo transfer_data.lo transfer_instr.lo transfer_token.lo transfer_word.lo transfer_word_list.lo trx_reader.lo tsx_reader.lo utf_converter.lo apertium_re.lo endian_double_util.lo transfer_mult.lo tmx_builder.lo -llttoolbox3 -lxml2 -lpcre
i686-linux-gnu-g++ -shared -nostdlib /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crti.o /usr/lib/gcc/i686-linux-gnu/4.6/crtbeginS.o .libs/collection.o .libs/constant_manager.o .libs/hmm.o .libs/interchunk.o .libs/interchunk_word.o .libs/lextor.o .libs/lextor_data.o .libs/lextor_eval.o .libs/lextor_word.o .libs/morpho_stream.o .libs/postchunk.o .libs/string_utils.o .libs/tagger.o .libs/tagger_data.o .libs/tagger_utils.o .libs/tagger_word.o .libs/transfer.o .libs/transfer_data.o .libs/transfer_instr.o .libs/transfer_token.o .libs/transfer_word.o .libs/transfer_word_list.o .libs/trx_reader.o .libs/tsx_reader.o .libs/utf_converter.o .libs/apertium_re.o .libs/endian_double_util.o .libs/transfer_mult.o .libs/tmx_builder.o /usr/lib/liblttoolbox3.so /usr/lib/i386-linux-gnu/libxml2.so -lpcre -L/usr/lib/gcc/i686-linux-gnu/4.6 -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../../lib -L/lib/i386-linux-gnu -L/lib/../lib -L/usr/lib/i386-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/i686-linux-gnu/4.6/../../.. -lstdc++ -lm -lc -lgcc_s /usr/lib/gcc/i686-linux-gnu/4.6/crtendS.o /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crtn.o -march=i686 -Wl,-Bsymbolic-functions -Wl,-z -Wl,relro -Wl,-soname -Wl,libapertium3-3.1.so.0 -o .libs/libapertium3-3.1.so.0.0.0
(cd .libs && rm -f libapertium3-3.1.so.0 && ln -s libapertium3-3.1.so.0.0.0 libapertium3-3.1.so.0)
(cd .libs && rm -f libapertium3.so && ln -s libapertium3-3.1.so.0.0.0 libapertium3.so)
ar cru .libs/libapertium3.a collection.o constant_manager.o hmm.o interchunk.o interchunk_word.o lextor.o lextor_data.o lextor_eval.o lextor_word.o morpho_stream.o postchunk.o string_utils.o tagger.o tagger_data.o tagger_utils.o tagger_word.o transfer.o transfer_data.o transfer_instr.o transfer_token.o transfer_word.o transfer_word_list.o trx_reader.o tsx_reader.o utf_converter.o apertium_re.o endian_double_util.o transfer_mult.o tmx_builder.o
ranlib .libs/libapertium3.a
creating libapertium3.la
/bin/sed: can't read /usr/lib/libxml2.la: No such file or directory
libtool: link: `/usr/lib/libxml2.la' is not a valid libtool archive
make[3]: *** [libapertium3.la] Error 1
make[3]: Leaving directory `/build/buildd/apertium-3.1.0/apertium'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/build/buildd/apertium-3.1.0/apertium'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/build/buildd/apertium-3.1.0'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20120204-0809
FAILED [dpkg-buildpackage died]
The full buidlog can be found at https://launchpad.net/ubuntu/+archive/test-rebuild-20120201/+build/3139265/+files/buildlog_ubuntu-precise-i386.apertium_3.1.0-1.3_FAILEDTOBUILD.txt.gz.
[1] http://people.ubuntuwire.org/~wgrant/rebuild-ftbfs-test/test-rebuild-20120201-precise.html
Can't repreduce this.