Doctest example failing

[pelson]

Looks like the doctests on master are failing...

 from /home/travis/build/SciTools/iris/docs/iris/src/userguide/regridding_plots/interpolate_column.py:

Traceback (most recent call last):

  File "/home/travis/miniconda/envs/test-environment/lib/python2.7/site-packages/matplotlib/sphinxext/plot_directive.py", line 517, in run_code

    six.exec_(code, ns)

  File "/home/travis/miniconda/envs/test-environment/lib/python2.7/site-packages/matplotlib/externals/six.py", line 672, in exec_

    exec("""exec _code_ in _globs_, _locs_""")

  File "<string>", line 1, in <module>

  File "<string>", line 13, in <module>

  File "/home/travis/miniconda/envs/test-environment/lib/python2.7/site-packages/Iris-2.0a0-py2.7.egg/iris/__init__.py", line 373, in load_cube

    raise iris.exceptions.ConstraintMismatchError(str(e))

ConstraintMismatchError: failed to merge into a single cube.

  cube.standard_name differs: u'air_potential_temperature' != u'surface_altitude'

  cube.var_name differs: u'air_potential_temperature' != u'surface_altitude'

  cube.units differs: Unit('K') != Unit('m')

  cube.attributes values differ for keys: 'STASH'

  cube.shape differs: (15, 100, 100) != (100, 100)

For example: https://travis-ci.org/SciTools/iris/jobs/293624098