Problem was in apache web server setting.
Because I am running a few web apps, I configure like followed.
/config/gitorious.yml
...
gitorious_host: git.mydomain.com
...
apache virtual host
root@gitserver:~ cat /etc/apache2/sites-enabled/gitorious
<VirtualHost *:80>
ServerName mydomain.com
ServerAlias git.mydomain.com
DocumentRoot /var/www/gitorious/public
Redirect permanent / https://git.mydomain.com/
#Redirect permanent / https://git.mydomain.com/ # if I comment this line, works fine
</VirtualHost>
It seems like that when client access git-server with git command, Apache web server is intercepting it.
Like another posts said, sub domain or web server setting is problem.