BUG: Expossing slicing bug with numpy

[cpelley]

This PR demonstrates the issue of a numpy bug i.e. adds two failing unittests to iris.
Unfortunately, the workaround discussed in the numpy issue does not appear to work in all circumstances.

Not for merging

@marqh @jkettleb @hdyson

[marqh]

hello @cpelley

this is not a test of Iris, this is a test of numpy; i don't think this test belongs in the Iris source code, i think it belongs with
numpy/numpy#8264

this is not a pattern used by iris, as far as I can see. Do you have examples of where Iris code makes use of this pattern that suffers from this behavioural problem?

mark

[cpelley]

...i don't think this test belongs in the Iris source code...

The purpose of this PR was not for merging but to demonstrate the numpy bug to iris users/developers which resulted from the recent dependency version increase on numpy by iris i.e. I wanted to increase its awareness.

Feel free to close this issue if you don't feel it provides any benefit. Alternatively a known failure unittest in iris might be useful rather than assuming that we remember to keep track of this numpy issue.

Cheers