rollback: use a hint for force

mercurial/localrepo.py

@@ -791,7 +791,7 b' class localrepository(repo.repository):'
         if not force and self['.'] != self['tip'] and desc == 'commit':
             raise util.Abort(
                 _('rollback of last commit while not checked out '
-                  'may lose data (use -f to force)'))
+                  'may lose data'), hint=_('use -f to force'))
 
         ui.status(msg)
         if dryrun:

tests/test-rollback.t

@@ -160,7 +160,8 b' that would lose data (issue2998)'
   $ hg update 0
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg rollback
-  abort: rollback of last commit while not checked out may lose data (use -f to force)
+  abort: rollback of last commit while not checked out may lose data
+  (use -f to force)
   [255]
   $ hg tip -q
   2:4d9cd3795eea