correct fix for override mistake

You inherited this bug from SES. We have since fixed it. You should too.

See https://github.com/Agoric/SES-shim/pull/409
See https://github.com/nodejs/node/commit/554ffa34320ebfe62e6eefd4607483866362efd3?short_path=85b6573#r42015196