tests failing on python 3.2

[Robert Collins]

(testtools-3.2)robertc@lifeless-64:~/source/unittest/testtools/working$ make check
PYTHONPATH=/home/robertc/source/unittest/testtools/working python -m testtools.run testtools.tests.test_suite
Tests running...
======================================================================
ERROR: testtools.tests.test_content.TestContent.test_from_file_with_simple_seek
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Traceback (most recent call last):
  File "testtools/tests/test_content.py", line 130, in test_from_file_with_simple_seek
    f.write('some data')
TypeError: 'str' does not support the buffer interface
======================================================================
ERROR: testtools.tests.test_content.TestContent.test_from_file_with_whence_seek
----------------------------------------------------------------------
Traceback (most recent call last):
  File "testtools/tests/test_content.py", line 140, in test_from_file_with_whence_seek
    f.write('some data')
TypeError: 'str' does not support the buffer interface
======================================================================
ERROR: testtools.tests.test_content.TestContent.test_from_stream_with_whence_seek
----------------------------------------------------------------------
Traceback (most recent call last):
  File "testtools/tests/test_content.py", line 184, in test_from_stream_with_whence_seek
    list(content.iter_bytes()), Equals(['data']))
  File "testtools/content.py", line 45, in _iter_chunks
    stream.seek(seek_offset, seek_whence)
IOError: Can't do nonzero cur-relative seeks

Ran 986 tests in 0.219s
FAILED (failures=3)
make: *** [check] Error 1