Failing timeseries tests on debian sparc buildbot
```
======================================================================
ERROR: test_to_timedelta_on_missing_values (pandas.tseries.tests.test_timedeltas.TestTimedeltas)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/tseries/tests/test_timedeltas.py", line 204, in test_to_timedelta_on_missing_values
    expected = Series([np.timedelta64(1000000000, 'ns'), timedelta_NaT], dtype='<m8[ns]')
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/core/series.py", line 218, in __init__
    raise_cast_failure=True)
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/core/series.py", line 2542, in _sanitize_array
    subarr = _try_cast(data, False)
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/core/series.py", line 2503, in _try_cast
    arr = _possibly_cast_to_datetime(arr, dtype)
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/core/common.py", line 1579, in _possibly_cast_to_datetime
    "cannot convert timedeltalike to dtype [%s]" % dtype)
TypeError: cannot convert timedeltalike to dtype [<m8[ns]]

======================================================================
FAIL: test_timedelta_ops_with_missing_values (pandas.tseries.tests.test_timedeltas.TestTimedeltas)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/tseries/tests/test_timedeltas.py", line 281, in test_timedelta_ops_with_missing_values
    assert_frame_equal(actual, dfn)
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/util/testing.py", line 493, in assert_frame_equal
    check_less_precise=check_less_precise)
  File "/home/buildslave/nd-bb-slave-sparc-sid/pandas-py3_x-sid-sparc/build/venv/lib/python3.3/site-packages/pandas-0.13.0rc1_124_g8cd34c6-py3.3-linux-sparc64.egg/pandas/util/testing.py", line 442, in assert_series_equal
    assert_almost_equal(left.values, right.values, check_less_precise)
  File "testing.pyx", line 58, in pandas._testing.assert_almost_equal (pandas/src/testing.c:2561)
  File "testing.pyx", line 93, in pandas._testing.assert_almost_equal (pandas/src/testing.c:1803)
  File "testing.pyx", line 107, in pandas._testing.assert_almost_equal (pandas/src/testing.c:2023)
AssertionError: First object is not null, second is null: numpy.timedelta64(9223372036854775807,'ns') != numpy.timedelta64('NaT','ns')
```

http://nipy.bic.berkeley.edu/builders/pandas-py3.x-sid-sparc/builds/491/steps/shell_4/logs/stdio
