Numpy versions < 1.8 play poorly with arrays of mixed type, truncating anything not of type string to the length of the longest string. This is inhibiting#7974

So the issue is as follows

>>>importnumpyasnp>>>np.__version__'1.7.1'>>>np.array(['A','A',np.nan,'B',-np.inf,3.14],dtype=np.unicode)array([u'A',u'A',u'n',u'B',u'-',u'3'],dtype='<U1')

two possible solutions:

1. Fold back in shims removed inRemove numpy 1.6 specific work-arounds #7484 that existed mainly to solve this problem
2. throw a warning if category.py is imported with a numpy<1.8 and skip tests for numpy<1.8

The advantage of 2 is it keeps the code cleaner and this is an edge case of sorts because it's only an issue when the array is of mixed type (strings and numbers). The advantage of 1 is of course edge case support on older systems.