composer安装问题，改了中国镜像还是不行

Question

linux下执行升级命令，出现提示The"https://getcomposer.org/version"filecouldnotbedownloaded:failedtoopenstream:HTTPrequestfailed!
root@linux:/opt/bitnami/apps/magento/htdocs#sudophp/opt/bitnami/php/bin/composer.pharself-update
[Composer\Downloader\TransportException]
The"https://getcomposer.org/version"filecouldnotbedownloaded:failedtoopenstream:HTTPrequestfailed!
self-update[-r|--rollback][--clean-backups][version]
查看/root/.composerconfig配置如下
{
"config":{
},
"repositories":[
{"type":"composer","url":"http://pkg.phpcomposer.com/repo/packagist/"},
{"packagist":false}
]
}
我更改了config配置，这个是中国镜像，但是不知道怎么升级还是这个提示。