title: TortoiseSVN downgrade issue from 1.8 to 1.7
body: <p>I was using the TortoiseSVN 1.7.11 client (Windows 7). I updated it to 1.8 and then it worked for some time with the 1.8 release. But other machines with which I'm working are still using 1.7.11, and I can't upgrade them so I thought of downgrading to 1.7.11. Now it's not working at all. I took a fresh checkout and it still asks to upgrade the working copy.</p>
  
  <p>When I click this option, it says "can't upgrade as it is not a pre-1.7 working copy directory. Missing default entry. I tried removing registries and delete configuration information from <code>%appdata%</code> folder too, but it doesn't fix the issue.</p>