On karmic, with bzr.dev r4479

jml@truth:~/src/bzr/trunk$ make
building extension modules.
python setup.py build_ext -i 
running build_ext
building 'bzrlib._bencode_pyx' extension
creating build
creating build/temp.linux-x86_64-2.6
creating build/temp.linux-x86_64-2.6/bzrlib
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.6 -c bzrlib/_bencode_pyx.c -o build/temp.linux-x86_64-2.6/bzrlib/_bencode_pyx.o
bzrlib/_bencode_pyx.c:2414: warning: ‘__Pyx_GetItemInt’ defined but not used
bzrlib/_bencode_pyx.c:2429: warning: ‘__Pyx_SetItemInt’ defined but not used
creating /home/jml/src/bzr/bzr.dev/bzrlib/bzrlib
gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions build/temp.linux-x86_64-2.6/bzrlib/_bencode_pyx.o -o /home/jml/src/bzr/bzr.dev/bzrlib/bzrlib/_bencode_pyx.so
pyrexc bzrlib/_btree_serializer_pyx.pyx --> bzrlib/_btree_serializer_pyx.c
/usr/lib/python2.6/dist-packages/Pyrex/Compiler/Scanning.py:39: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import md5
building 'bzrlib._btree_serializer_pyx' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.6 -c bzrlib/_btree_serializer_pyx.c -o build/temp.linux-x86_64-2.6/bzrlib/_btree_serializer_pyx.o
bzrlib/_btree_serializer_pyx.c: In function ‘__pyx_f_6bzrlib_21_btree_serializer_pyx_safe_string_from_size’:
bzrlib/_btree_serializer_pyx.c:187: warning: cast from pointer to integer of different size
bzrlib/_btree_serializer_pyx.c: In function ‘__pyx_f_6bzrlib_21_btree_serializer_pyx_safe_interned_string_from_size’:
bzrlib/_btree_serializer_pyx.c:239: warning: cast from pointer to integer of different size
...

On karmic with 1.16,

jml@truth:~/src/bzr/bzr.1.16$ make 
building extension modules.
python setup.py build_ext -i 
running build_ext
building 'bzrlib._bencode_pyx' extension
creating build
creating build/temp.linux-x86_64-2.6
creating build/temp.linux-x86_64-2.6/bzrlib
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.6 -c bzrlib/_bencode_pyx.c -o build/temp.linux-x86_64-2.6/bzrlib/_bencode_pyx.o
bzrlib/_bencode_pyx.c:2414: warning: ‘__Pyx_GetItemInt’ defined but not used
bzrlib/_bencode_pyx.c:2429: warning: ‘__Pyx_SetItemInt’ defined but not used
creating /home/jml/src/bzr/bzr.1.16/bzrlib/bzrlib
gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions build/temp.linux-x86_64-2.6/bzrlib/_bencode_pyx.o -o /home/jml/src/bzr/bzr.1.16/bzrlib/bzrlib/_bencode_pyx.so
building 'bzrlib._btree_serializer_c' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.6 -c bzrlib/_btree_serializer_c.c -o build/temp.linux-x86_64-2.6/bzrlib/_btree_serializer_c.o
bzrlib/_btree_serializer_c.c: In function ‘__pyx_f_19_btree_serializer_c_safe_string_from_size’:
bzrlib/_btree_serializer_c.c:144: warning: cast from pointer to integer of different size
bzrlib/_btree_serializer_c.c: In function ‘__pyx_f_19_btree_serializer_c_safe_interned_string_from_size’:
bzrlib/_btree_serializer_c.c:200: warning: cast from pointer to integer of different size
bzrlib/_btree_serializer_c.c: At top level:
bzrlib/_btree_serializer_c.c:1607: warning: ‘__Pyx_GetItemInt’ defined but not used
bzrlib/_btree_serializer_c.c:1685: warning: ‘__Pyx_SetItemInt’ defined but not used
...