Error in documentation for @{-n} in gitrevisions

While discussing the behavior of "git checkout -", I apparently was
confused because the documentation states:

  The construct @{-<n>} means the <n>th branch checked out before the
current one.

But experimenting with it, it also takes you back to previously
checkout commits.

  git-checkout-at-minus-one :: (master) » git checkout origin/master
  Note: checking out 'origin/master'.
  HEAD is now at f8b2f0c... two

  git-checkout-at-minus-one :: (f8b2f0c) » git checkout -
  Switched to branch 'master'

  git-checkout-at-minus-one :: (master) » git checkout -
                                              Note: checking out
'f8b2f0c1419d1fe798159c2c2578d2dbe1323148'.
  HEAD is now at f8b2f0c... two

Either the documentation is wrong, and should be changed to "<n>th
branch/commit checkout out before the current one", or the behavior of
@{-1} is wrong.