Upgraded from v0.4 to v0.9 - EllipseSkyRegion no longer hashable?

[DavidT3]

Hi!

First off, thanks for making this module, it has been very useful in my own software. I've been very bad at keeping dependencies updated, and have recently started updating them all. Testing highlighted a problem and throws an error:

TypeError: unhashable type: 'EllipseSkyRegion'

I'm wondering if this was a deliberate behaviour change?

I was essentially using an intersection between two sets to determine which region instances where present in both, which I should be able to achieve in other ways (I believe the region class has an eq method implemented), but using the sets and intersection was neat.