Cleanup: Using set for faster performance.

package_manager/networking.py

@@ -177,7 +177,7 @@ class WM_OT_update_index(bpy.types.Operator):
         for name, content in addon_list["addons"].items():
             # Skip add-ons not installed to USER path
             # TODO: support above later
-            for a in installed:
+            for a in set(installed):
                 if name == a.__name__ and user_path not in a.__file__:
                     log.info("Not listing add-on %s, as it is installed to "
                                 "location other than USER path", name)