#5876 broken pipe handling

[melfa]

    # how to reproduce bug
    # first set up redis timeout to 5 seconds in /etc/redis/redis.conf as described in http://redis.io/topics/clients
    $redisConfig = [
        'hostname' => 'localhost',
        'port' => 6379,
        'connectionTimeout' => 5,
    ];
    $redis = new \yii\redis\Connection($redisConfig);
    $redis->executeCommand('PING');

    sleep(20);

    try {
        // this is will cause yii\db\Exception in Connection::parseResponse since Redis dropped connection
        $redis->executeCommand('PING');
    }
    catch (\Exception $e) {
        // now Connection::close will try to send QUIT command but got yii\base\ErrorException
        // in Connection::executeCommand on fwrite
        // So we can't send any command and can't close connection
        $redis->close();
    }

[cebe]

pull request needs to be merged into redis extension. Added a note to the issue: yiisoft/yii2-redis#57