title: Cannot checkout branch from GitHub forked repository
body: <p>I am trying to checkout a branch from my forked repository but it gives an error:</p>
  
  <p>Repository: <a href="https://github.com/tmsblgh/codechecker/tree/issue799" rel="nofollow noreferrer">https://github.com/tmsblgh/codechecker/tree/issue799</a></p>
  
  <pre><code>MacBook-Pro:codechecker tmsblgh$ git branch -vv
  * master acdc482 [origin/master] Merge pull request #1636 from gyorb/version68
  MacBook-Pro:codechecker tmsblgh$ git --version
  git version 2.17.1
  MacBook-Pro:codechecker tmsblgh$ git fetch
  MacBook-Pro:codechecker tmsblgh$ git checkout issue799
  error: pathspec 'issue799' did not match any file(s) known to git.
  Baloghs-MacBook-Pro:codechecker tmsblgh$ git remote -v
  origin  https://github.com/tmsblgh/codechecker.git (fetch)
  origin  https://github.com/tmsblgh/codechecker.git (push)
  MacBook-Pro:codechecker tmsblgh$ git checkout issue799
  error: pathspec 'issue799' did not match any file(s) known to git.
  </code></pre>