Currently, if an unversioned directory is present where we would expect
a versioned repository to be, the following error is printed:

  Can't update/checkout %s if an unversioned directory is present.
  Delete the directory and try again.

If --reset and --delete_unversioned_trees are used, gclient should delete
the unversioned directory in this case.

This problem can be reproduced using the following recipe:
  $ rm -rf src/third_party/webrtc/.svn
  $ gclient sync -nRftD

BUG=none
TEST=Verify that above error is fixed. Run all smoke tests.


Review URL: https://chromiumcodereview.appspot.com/11366239

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@167942 0039d316-1c4b-4281-b951-d872f2087c98