Failing to import macfsn is not a fatal error.

Mac/Python/macmain.c

@@ -405,6 +405,7 @@ PyMac_InstallNavServicesForSF(void)
 			else {
 				PySys_WriteStderr("use -v for traceback\n");
 			}
+			PyErr_Clear();
 		}
 	}
 }