message: [Tests] Debug assert_raises_rpc_error
diff: @@ -115,7 +115,7 @@ def try_rpc(code, message, fun, *args, **kwds):
  if (code is not None) and (code != e.error["code"]):
  raise AssertionError("Unexpected JSONRPC error code %i" % e.error["code"])
  if (message is not None) and (message not in e.error['message']):
  - raise AssertionError("Expected substring not found:" + e.error['message'])
  + raise AssertionError("Expected substring (%s) not found in: %s" % (message, e.error['message']))
  return True
  except Exception as e:
  raise AssertionError("Unexpected exception raised: " + type(e).__name__)
  