update cfg mgr exit method (puzzle#92)

plugins/module_utils/config_utils.py

@@ -160,6 +160,13 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             RuntimeError: If there are unsaved changes in the configuration.
         """
         if exc_type:
+            # module.fail_json will always yield a SystemExit exception
+            # we need to raise this exception "as is" to avoid ansible warnings
+            # If however an unexpected exception was risen which was not a result of
+            # module.fail_json raising this warning is ok, and we need the exceptions
+            # details to troubleshoot the issue
+            if isinstance(exc_val, SystemExit):
+                raise
             raise exc_type(f"Exception occurred: {exc_val}")
         if self.changed and not self._check_mode:
             raise RuntimeError("Config has changed. Cannot exit without saving.")