I have a failing test on my box:

```
======================================================================
FAIL: Test adding distances to source space
----------------------------------------------------------------------
Traceback (most recent call last):
  File
"/Users/alex/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/nose/case.py",
line 197, in runTest
    self.test(*self.arg)
  File
"/Users/alex/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/numpy/testing/decorators.py",
line 146, in skipper_func
    return f(*args, **kwargs)
  File
"/Users/alex/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/numpy/testing/decorators.py",
line 146, in skipper_func
    return f(*args, **kwargs)
  File "/Users/alex/work/src/mne-python/mne/tests/test_source_space.py",
line 125, in test_add_source_space_distances
    assert_array_equal(so['dist_limit'], np.array([-0.007], np.float32))
  File
"/Users/alex/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/numpy/testing/utils.py",
line 718, in assert_array_equal
    verbose=verbose, header='Arrays are not equal')
  File
"/Users/alex/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/numpy/testing/utils.py",
line 644, in assert_array_compare
    raise AssertionError(msg)
AssertionError:
Arrays are not equal

(mismatch 100.0%)
 x: array(None, dtype=object)
 y: array([-0.007], dtype=float32)
```