benchmarks.py: add a runtime error if the format output is wrong

Author: tsolomko

benchmarks.py

@@ -342,6 +342,8 @@ def action_run(args):
                         print(result.str_compare(base_result))
                     else:
                         print(result)
+                else:
+                    raise RuntimeError("Unexpected format of the output")
 
     if base is not None:
         print(stat_keeper.summary())