Address useless-return.

.pylintrc

@@ -420,7 +420,6 @@ disable=raw-checker-failed,
         use-dict-literal,
         use-list-literal,
         useless-object-inheritance,
-        useless-return,
         # Cannot remove yet due to inadequacy of rules
         inconsistent-return-statements,  # doesn't notice that fail_json() does not return
 

plugins/modules/docker_swarm.py

@@ -504,7 +504,7 @@ class SwarmManager(DockerBaseClass):
             unlock_key = self.get_unlock_key()
             self.swarm_info.update(unlock_key)
         except APIError:
-            return
+            pass
 
     def get_unlock_key(self):
         default = {"UnlockKey": None}