Headers_in and Headers_out returns wrong value in some case

[yano3]

When there are multiple headers where one name contains the other (e.g. X-HOGE and X-HOGE-FUGA), Headers_in, Headers_out returns wrong value.

Reproduce

server {
    listen       80;
    server_name  localhost;

    location / {
        mruby_content_handler_code '
          hin = Nginx::Headers_in.new
          Nginx.echo hin["X-HOGE"]
          Nginx.echo hin["X-HOGE-FUGA"]
        ';
    }
}

$ curl -H "X-HOGE: hoge" -H "X-HOGE-FUGA: fuga" http://localhost:10080/index.html
["hoge", "fuga"]
fuga

In the above example, Nginx.echo hin["X-HOGE"] is expected to return only hoge.