git-rebase.sh: fix typo in an error message

Fix a typo in the error messages which is shown if it seems that a
rebase is already in progress.

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase.sh

@@ -348,7 +348,7 @@ then
 	cmd_clear_stale_rebase="rm -fr \"$state_dir\""
 	die "
 $(eval_gettext 'It seems that there is already a $state_dir_base directory, and
-I wonder if you ware in the middle of another rebase.  If that is the
+I wonder if you are in the middle of another rebase.  If that is the
 case, please try
 	$cmd_live_rebase
 If that is not the case, please