code: func (c *Client) condRelease(cn *conn, err *error) {
  	switch *err {
  	case nil, ErrCacheMiss, ErrCASConflict, ErrNotStored, ErrBadIncrDec:
  		c.putFreeConn(cn)
  	default:
  		cn.nc.Close()
  	}
  }
docs: // condRelease releases this connection if the error pointed to by err
  // is is nil (not an error) or is only a protocol level error (e.g. a
  // cache miss).  The purpose is to not recycle TCP connections that
  // are bad.