python: Add pylint check W0109 (duplicate-key)

Duplicated dict keys will silently override one another.

.pylintrc

@@ -67,6 +67,7 @@ disable=all
 # multiple time (only on the command line, not in the configuration file where
 # it should appear only once). See also the "--disable" option for examples.
 enable=dangerous-default-value, # W0102
+       duplicate-key, # W0109
        wildcard-import, # W0401
        assert-on-tuple, # W0199
        unused-import, # W0611

src/python/espressomd/reaction_methods.py

@@ -503,16 +503,10 @@ def get_status(self):
         """
 
         self.check_reaction_method()
-        reactions_list = []
-
-        for reaction in self.reactions:
-            reaction = {"reactant_coefficients": reaction.reactant_coefficients,
-                        "reactant_types": reaction.reactant_types,
-                        "product_types": reaction.product_types,
-                        "product_coefficients": reaction.product_coefficients,
-                        "reactant_types": reaction.reactant_types,
-                        "gamma": reaction.gamma}
-            reactions_list.append(reaction)
+        property_keys = {"reactant_coefficients", "reactant_types",
+                         "product_coefficients", "product_types", "gamma"}
+        reactions_list = [{key: getattr(reaction, key) for key in property_keys}
+                          for reaction in self.reactions]
 
         return {"reactions": reactions_list, "kT": self.kT,
                 "exclusion_range": self.exclusion_range,