Fix an unbound variable in ChainedDiscretizationConnection.

Also test ChainedDiscretizationConnection, because it doesn't look like it is being tested.

added 1 commit

• 18540dd3 - flake8 fix

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Ouch. I "fixed" ChainedDiscrConn not working for empty connections in "drive-by-mode" a while ago. I was concerned about no tests but didn't think further about it. Thanks for taking care of this!

enabled an automatic merge when the pipeline for 18540dd3 succeeds

merged

mentioned in commit 02ff7d8e