Small bug fix in checks of sort_non_coupled_nodes()

Former-commit-id: bf551ed627e53299f7e10400ab4681ed063696cd

kadmos/graph/graph_data.py

@@ -491,11 +491,11 @@ class DataGraph(KadmosGraph):
         for func in nodes:
             assert func in self, "Function node {} must be present in graph.".format(func)
         subgraph = self.get_subgraph_by_function_nodes(nodes)
+        subgraph = subgraph.get_function_graph()
         assert nx.is_directed_acyclic_graph(subgraph)
 
         # Make sure the nodes are in a topological sort
-        if self.check_for_coupling(nodes, only_feedback=True):
-            nodes = nx.topological_sort(subgraph)
+        nodes = nx.topological_sort(subgraph)
 
         nodes_to_sort = list(nodes)
         sorted_nodes = []