Fixed handling of a list of coupling_maps passed to transpile()

[wshanks]

Closes #9885

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[wshanks]

I can't think of why you would really want to pass a list of different coupling maps to transpile and I see that doing so is already marked for deprecation. I think the main benefit of this PR is sparing someone else like me from staring at these lines trying to figure how they could work 🙂

[mtreinish]

Lol, yeah that could never work, that definitely slipped through on review in #7789. I guess it kind of confirms the argument broadcasting in transpile() is not widely used. Since this is technically a bugfix it'd be good to have a test case to cover this (it's definitely not worth a release note). Do you mind adding a quick test that is using this deprecated functionality?

[coveralls]

Pull Request Test Coverage Report for Build 4574928928

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 37 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.01%) to 85.41%

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Files with Coverage Reduction	New Missed Lines	%
qiskit/transpiler/preset_passmanagers/level3.py	5	92.5%
qiskit/circuit/quantumcircuitdata.py	14	87.04%
qiskit/test/base.py	18	84.03%

Totals
Change from base Build 4569011817:	0.01%
Covered Lines:	67393
Relevant Lines:	78905

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💛 - Coveralls

[wshanks]

Yes, adding a test is a good idea, especially since my first pass at the PR was broken 🙂

[wshanks]

I added a test but it failed because it triggers the deprecation warning. How should one test code that triggers a deprecation warning?

[jakelishman]

Wrap the call that warns in a with self.assertWarnsRegex block asserting suitable things about the warning - it serves double duty by testing that the warning fires correctly, while allowing the code within it.

[mtreinish]

LGTM, thanks for adding the test