title: Git: per-branch level access and maximum number of branches
body: <p>I have a few Git/Github questions. First, is there a way to create some kind of access token for pull/push access to just <strong>one</strong> branch on a Git repo? The idea is I'd give a user this access token, and they can use it but only to push/pull on one branch that I've specified in advance.</p>
  
  <p>Second, is there a upper bound on the number of branches a repo can have? Say I have 100 branches. Does this impact performance? What about 10,000? 1,000,000 branches?</p>