test_breakin fails on wine: failed to send CTRL_BREAK: Invalid function

[Martin Pool]

This seems quite reproducible on wine 1.3. Maybe we should just skip the test there.

ERROR: bzrlib.tests.blackbox.test_breakin.TestBreakin.test_breakin
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_StringException: Text attachment: log
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Text attachment: traceback
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Traceback (most recent call last):
  File "Z:\home\mbp\lib\python\testtools\runtest.py", line 144, in _run_user
    return fn(*args)
  File "Z:\home\mbp\lib\python\testtools\testcase.py", line 465, in _run_test_method
    testMethod()
  File "Z:\home\mbp\bzr\trunk\bzrlib\tests\blackbox\test_breakin.py", line 155, in test_breakin
    self._send_signal(proc.pid, 'break')
  File "Z:\home\mbp\bzr\trunk\bzrlib\tests\blackbox\test_breakin.py", line 85, in _send_signal_win32
    % (err,))
RuntimeError: failed to send CTRL_BREAK: Invalid function