title: SSHD config: PermitUserEnvironment on a case-by-case basis
body: <p>I have a git server where people set up remote repositories over ssh, and there's a git user that they all connect as which has secure permissions and whatnot.</p>
  <p>I'm editing the pre-receive hook in a repo so that it sees if the environment variable, <code>$GIT_USER</code>, matches the list of allowed users for that repo to prevent unauthorized users from pushing.</p>
  <p>This environment variable is set individually in the git user's <code>.ssh/authorized_keys</code> file.</p>
  <p>However, I don't want environment variables to be set for ssh for any user besides git.</p>
  <p>Is there any way to edit <code>/etc/ssh/sshd_config</code> such that <code>PermitUserEnvironment</code> is only enabled for the git user?</p>