Fix global phase tracking around DAGCircuit.substitute_node. (bp #5618)

[mergify]

This is an automatic backport of pull request #5618 done by Mergify.

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Changes to be committed:
	modified:   qiskit/circuit/quantumcircuit.py
	modified:   qiskit/dagcircuit/dagcircuit.py
	modified:   qiskit/transpiler/passes/basis/basis_translator.py
	modified:   qiskit/transpiler/passes/basis/unroller.py
	new file:   releasenotes/notes/dagcircuit-fix-substitute-node-global-phase-usage-ee05476a7d0b24c6.yaml
	modified:   test/python/circuit/library/test_grover_operator.py
	modified:   test/python/circuit/test_circuit_qasm.py
	modified:   test/python/transpiler/test_unroller.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   test/python/compiler/test_transpiler.py
	both modified:   test/python/transpiler/test_basis_translator.py

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[mtreinish]

Actually, looking at this more closely with fresh eyes I think we should remove the __eq__ changes from a backport because it's potentially a disruptive upgrade for users

[mtreinish]

I think this isn't correct on stable/0.16, the global phase of pi was added to the grover operator in #5517: https://github.com/Qiskit/qiskit-terra/pull/5517/files#diff-5cc16ff691e55c7c0e9d381f48c31157dcc945f3107f4e6ea246b2a2bcce986e we should check with @Cryoris if that needs to be backported too or not

[Cryoris]

I think we can include that phase change from 5517, since then the Grover operator fits the definition from the papers 🙂

[mtreinish]

ok, I'll add that here then