git-rebase: clean up dashed-usages in messages

Signed-off-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase.sh

@@ -9,7 +9,7 @@ OPTIONS_STUCKLONG=t
 OPTIONS_SPEC="\
 git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] [<upstream>] [<branch>]
 git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] --root [<branch>]
-git-rebase --continue | --abort | --skip | --edit-todo
+git rebase --continue | --abort | --skip | --edit-todo
 --
  Available options are
 v,verbose!         display a diffstat of what changed upstream
@@ -214,7 +214,7 @@ run_pre_rebase_hook () {
 }
 
 test -f "$apply_dir"/applying &&
-	die "$(gettext "It looks like git-am is in progress. Cannot rebase.")"
+	die "$(gettext "It looks like 'git am' is in progress. Cannot rebase.")"
 
 if test -d "$apply_dir"
 then