[entity] comparing two entities returns NotImplemented
Fixes a test when using some versions of unittest2, where
assertItemsEqual tries a sort and expects TypeError, which it doesn't
get if we directly raise NotImplementedError. The NotImplemented value
is treated specially by the interpreter:
https://docs.python.org/3.4/library/constants.html#NotImplemented
Release notes
-------------
.. toctree::
:maxdepth: 1
3.22
3.21
3.20
3.19
3.18
3.17
3.16
3.15
3.14