**Description of the issue** If you create a PauliString ``` p = cirq.PauliString({q2: cirq.Z, q1: cirq.Y, q0: cirq.X}) ``` and round trip it via its repr, the qubit order does not match. ``` eval(repr(p)).qubits == p.qubits >>> False ``` PauliString having ordered qubits was introduced in #4270
