Transpiler effiency bug in synthesis

Information

• Qiskit Terra version: qiskit-terra==0.18.2
• Python version: 3.9.7
• Operating system: CentOS Linux 7 (Core)

What is the current behavior?

/home/user/.conda/envs/stuff/lib/python3.9/site-packages/qiskit/transpiler/runningpassmanager.py:166: UserWarning: Resynthesized [<qiskit.dagcircuit.dagnode.DAGNode object at 0x2ae0e3027820>, <qiskit.dagcircuit.dagnode.DAGNode object at 0x2ae0e3aae8e0>] and got global phase: π/2, but the original was native 
and the new value is longer.  This indicates an efficiency bug in synthesis.  Please report it by opening an issue here: https://github.com/Qiskit/qiskit-terra/issues/new/choose
  new_dag = pass_.run(dag)

This circuit was also in the messsage:

Steps to reproduce the problem

I got this warning several times while using the qiskit transpiler. I am not able to retrieve the exact circuit that caused this error.

What is the expected behavior?

Suggested solutions

[epelofske-LANL]

I found a circuit which gave the user warning (edit; the user warning was the same as the above post, and is the same as the original start to this issue):

circuit.txt

The transpiler call I made that produced the warning used several options, including specifying the coupling map of ibmq_guadalupe:

backend = provider.get_backend("ibmq_guadalupe")
config = backend.configuration()
hardware_connectivity = networkx.Graph(config.coupling_map)
compiled_circuit = transpile(qc, coupling_map=CouplingMap(list(hardware_connectivity.edges())), optimization_level=3, basis_gates=["x", "sx", "cx", "rz"], initial_layout=[8, 11, 12, 13, 14, 15])

[epelofske-LANL]

I installed from source, and managed to get this warning:

/home/user/.local/lib/python3.9/site-packages/qiskit/transpiler/passes/optimization/optimize_1q_decomposition.py:171: UserWarning: Resynthesized 

Instruction(name='sx', num_qubits=1, num_clbits=0, params=[])
Instruction(name='x', num_qubits=1, num_clbits=0, params=[])

and got

Instruction(name='rz', num_qubits=1, num_clbits=0, params=[-3.141592653589793])
Instruction(name='sx', num_qubits=1, num_clbits=0, params=[])
Instruction(name='rz', num_qubits=1, num_clbits=0, params=[-3.141592653589793])

but the original was native (for ['x', 'sx', 'cx', 'rz']) and the new value is longer.  This indicates an efficiency bug in synthesis.  Please report it by opening an issue here: https://github.com/Qiskit/qiskit-terra/issues/new/choose
  if new_circ is not None and self._substitution_checks(dag, run, new_circ, new_basis):

I am trying to save a circuit which gives this warning, and will post it here if I can replicate it (it seems to be hard to replicate).