Test failure in matplotlib.tests.test_colors.test_cmap_and_norm_from_levels_and_colors2

[mdboom]

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ERROR: matplotlib.tests.test_colors.test_cmap_and_norm_from_levels_and_colors2
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Traceback (most recent call last):
  File "/home/travis/virtualenv/python3.2/lib/python3.2/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/travis/virtualenv/python3.2/lib/python3.2/site-packages/matplotlib-1.4.x-py3.2-linux-x86_64.egg/matplotlib/tests/test_colors.py", line 134, in test_cmap_and_norm_from_levels_and_colors2
    np.ma.array(1, mask=True): bad}),
TypeError: unhashable type: 'MaskedArray'
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Probably related to #2050. Cc: @pelson

[mdboom]

Closed by #2080