working tree are kept, so that they can be committed to the
<branch>.
+
+If <branch> is not found but there does exist a tracking branch in
+exactly one remote (call it <remote>) with a matching name, treat as
+equivalent to
++
+------------
+$ git checkout -b <branch> --track <remote>/<branch>
+------------
++
You could omit <branch>, in which case the command degenerates to
"check out the current branch", which is a glorified no-op with a
rather expensive side-effects to show only the tracking information,