Remove deepcopies from DAGCircuit.__eq__ (Qiskit#4992)

The __eq__ method of the dagcircuit class was previously deep copying
the retworkx PyDAG objects for both self and other to force a reindexing
of the node indices in the graphs to acvoid a bug in retworkx (see
Qiskit/rustworkx#27 for more details). In the next retworkx a workaround
for that bug was introduced which removes the need for doing the deepcopy
calls. This commit does that and removes the deep copies which should
improve the performance of run __eq__ o dagcircuit objects.

qiskit/dagcircuit/dagcircuit.py

@@ -783,12 +783,8 @@ def _full_pred_succ_maps(self, pred_map, succ_map, input_circuit,
         return full_pred_map, full_succ_map
 
     def __eq__(self, other):
-        # TODO remove deepcopy calls after
-        # https://github.com/mtreinish/retworkx/issues/27 is fixed
-        slf = copy.deepcopy(self._multi_graph)
-        oth = copy.deepcopy(other._multi_graph)
-
-        return rx.is_isomorphic_node_match(slf, oth,
+        return rx.is_isomorphic_node_match(self._multi_graph,
+                                           other._multi_graph,
                                            DAGNode.semantic_eq)
 
     def topological_nodes(self):

requirements.txt

@@ -1,7 +1,7 @@
 contextvars>=2.4;python_version<'3.7'
 jsonschema>=2.6
 networkx>=2.2
-retworkx>=0.4.0
+retworkx>=0.5.0
 numpy>=1.17
 ply>=3.10
 psutil>=5

setup.py

@@ -26,7 +26,7 @@
     "contextvars>=2.4;python_version<'3.7'",
     "jsonschema>=2.6",
     "networkx>=2.2",
-    "retworkx>=0.4.0",
+    "retworkx>=0.5.0",
     "numpy>=1.17",
     "ply>=3.10",
     "psutil>=5",