Please note that this commit contains an API change and the CVS/SVN plugins need to be updated to 1.1.0-SNAPSHOT to work properly.
I should also mention that this behaves somewhat differently depending on the Team Provider.
For Git, it reverts to HEAD in refs/remotes/origin/[branch] discarding any local commits and untracked files
For SVN it is a local operation. All modifications are reverted and all remaining untracked files are deleted
For CVS it's a mess that does an update -C (clean working copy)