We use Gitolite (http://gitolite.com/gitolite/index.html http://gitolite.com/gitolite/index.html). It can be configured to block (force) pushes for repositories

We use Gitolite (http://gitolite.com/gitolite/index.html http://gitolite.com/gitolite/index.html). It can be configured to block (force) pushes for repositories, branches or persons, among other things.