Aesara 2.2.0 release broke tests on main

[michaelosthege]

Description of your problem

The recent merge of #4955 broke lots of tests on main:
https://github.com/pymc-devs/pymc3/actions/runs/1153556997

The authors & reviewers of #4955 are not to blame though, because over there the CI was green ✔ on 2021-08-19T17-33Z.

At 2021-08-19T19-37Z (two hours later) however a new Aesara version 2.2.0 was released.

The next CI run was on main after the merge and blew up.`

The automated PR #4960 has a red CI because of this.

Versions and main components

• PyMC3 Version: main
• Aesara/Theano Version: 2.2.0

[twiecki]

I suppose the question is whether it's an intentional API breakage (in which case we need to fix PyMC3) or an apsara issue.

[michaelosthege]

There are tons of failures in the CI, so I don't know if it's the only breakage, but this quote from the release notes definitely has a lot of consequences:

TensorConstant is now a subclass of TensorVariable

Code that was previously using isinstance(..., TensorVariable) as a means of filtering out TensorConstants will need to be updated

[twiecki]

So we probably need to go through our isinstance checks.

[michaelosthege]

quick fix to pin the version <2.2.0 so we don't stall out the other PRs?

[twiecki]

Good idea.