}
		if !req.keepConn {
			// connection will close upon return
			return errCloseConn
		}
		return nil
	default:
		b := make([]byte, 8)
		b[0] = byte(rec.h.Type)
		c.conn.writeRecord(typeUnknownType, 0, b)
		return nil
	}
}

// filterOutUsedEnvVars returns a new map of env vars without the
// variables in the given envVars map that are read for creating each http.Request