title: Locking a SubVersion branch in the days before a release
body: <p>In the days before a release we'd like to be able to prevent developers from committing files to the SubVersion branch, unless a team leader has reviewed and approved the changes (in which case they would make a temporary change to allow this).</p>
  
  <p>Previously we used ClearCase, in which this was relatively easy to do.</p>
  
  <p>Since the svn:lock command only works on a per-file basis, we are uncertain if we can emulate this behaviour in SubVersion.</p>
  
  <p>What do you do?</p>