我已经安装了 ElasticSearch 1.7 并想安装 marvel，下面的命令安装许可证有效。
sudo bin/plugin --install mobz/elasticsearch-head --verbose
但是安装奇迹本身失败了：
vagrant@homestead:/usr/share/elasticsearch$ sudo bin/plugin install marvel-agent
-> Installing marvel-agent...
Trying https://github.com/null/marvel-agent/archive/master.zip...
Failed to install marvel-agent, reason: failed to download out of all possible locations..., use --verbose to get detailed information
如何解决这个问题？发生了--verbose这种情况vagrant@homestead:/usr/share/elasticsearch$ sudo bin/plugin install marvel-agent --verbose
-> Installing marvel-agent...
Trying https://github.com/null/marvel-agent/archive/master.zip...
Failed: IOException[Can't get https://github.com/null/marvel-agent/archive/master.zip to /usr/share/elasticsearch/plugins/marvel-agent.zip]; nested: FileNotFoundException[https://github.com/null/marvel-agent/archive/master.zip]; nested: FileNotFoundException[https://github.com/null/marvel-agent/archive/master.zip];
Failed to install marvel-agent, reason: failed to download out of all possible locations..., use --verbose to get detailed information