Fix: Remove unknown variable in error message. (Redmine issue: #7577)

lib/mentat/module/detmngr.py

@@ -267,7 +267,7 @@ class MentatDetmngrScript(mentat.script.fetcher.FetcherScript):
         :rtype: dict
         """
         if 'clients' not in detectors_file_data:
-            raise pyzenkit.zenscript.ZenScriptException("Invalid detectors file '{}' format, expected 'clients' key.".format(detectors_file))
+            raise pyzenkit.zenscript.ZenScriptException("Invalid detectors file format, expected 'clients' key.")
         processed_data = collections.defaultdict(dict)
         for client in detectors_file_data['clients']:
             det = mentat.datatype.internal.t_detector_record(client, source = detectors_file_type)