Apply adjust_no_electric_network on a copy of etrago.network to avoid…

… conflics when it is applied for the market model

etrago/cluster/electrical.py

@@ -116,7 +116,7 @@ def adjust_no_electric_network(etrago, busmap, cluster_met):
     busmap : dict
         Maps old bus_ids to new bus_ids including all sectors.
     """
-    network = etrago.network
+    network = etrago.network.copy()
     # network2 is supposed to contain all the not electrical or gas buses 
     # and links
     network2 = network.copy(with_time=False)