Fix qpy for controlled UnitaryGate

[ElePT]

Summary

Fixes #10802. QPY was failing to deserialize the NUMPY_OBJ from the unitary gate definition because it was looking for the clbits of a circuit that, in that scope, was None.

Details and comments

I am not too happy about having to decompose the circuit so many times for the test. I get that after #10758, the uuid is appended to the name of the gate, which makes the circuits not equal:

>>> qc.data
[CircuitInstruction(operation=Instruction(name='c-unitary', num_qubits=2, num_clbits=0, params=[array([[0.+0.j, 1.+0.j],
       [1.+0.j, 0.+0.j]])]), qubits=(Qubit(QuantumRegister(2, 'q'), 0), Qubit(QuantumRegister(2, 'q'), 1)), clbits=())]
>>> qc2.data
[CircuitInstruction(operation=Instruction(name='c-unitary_781f2d2b-cd9a-4d8e-b38a-59d141b82ebc', num_qubits=2, num_clbits=0, params=[array([[0.+0.j, 1.+0.j],
       [1.+0.j, 0.+0.j]])]), qubits=(Qubit(QuantumRegister(2, 'q'), 0), Qubit(QuantumRegister(2, 'q'), 1)), clbits=())]

But I'm not sure why, for example, decomposing once fails:

>>> qc.decompose(reps=1).data
[CircuitInstruction(operation=Instruction(name='circuit-121_dg', num_qubits=2, num_clbits=0, params=[]), qubits=(Qubit(QuantumRegister(2, 'q'), 0), Qubit(QuantumRegister(2, 'q'), 1)), clbits=())]
>>> qc2.decompose(reps=1).data
[CircuitInstruction(operation=Instruction(name='circuit-121_dg', num_qubits=2, num_clbits=0, params=[]), qubits=(Qubit(QuantumRegister(2, 'q'), 0), Qubit(QuantumRegister(2, 'q'), 1)), clbits=())]

[qiskit-bot]

One or more of the the following people are requested to review this:

• @Qiskit/terra-core
• @mtreinish
• @nkanazawa1989

[coveralls]

Pull Request Test Coverage Report for Build 6144717289

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 15 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.01%) to 87.282%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	3	91.41%
crates/qasm2/src/parse.rs	12	96.67%

Totals
Change from base Build 6124202354:	-0.01%
Covered Lines:	74469
Relevant Lines:	85320

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💛 - Coveralls

[mtreinish]

The fix LGTM, but there were some merge conflicts that need to be resolved. This also might have a conflict with #10898 but I assume this will merge before that, so I'll fix it in #10898 when this merges.

[mtreinish]

Thanks for the quick update.

(oh there is still a merge conflict)

[mtreinish]

This LGTM, thanks for the update, but I'll hold off on the merge queue because something looks weird with the last rebase, it pulled in a bunch of unrelated commits to your branch.