git-sh-setup: remove messaging supporting --preserve-merges

Remove messages that were last used by the code removed in
a74b35081c5 (rebase: drop support for `--preserve-merges`,
2021-09-07).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-sh-setup.sh b/git-sh-setup.sh
index cee053c..960982f 100644
--- a/git-sh-setup.sh
+++ b/git-sh-setup.sh
@@ -217,9 +217,6 @@
 	then
 		action=$1
 		case "$action" in
-		rebase)
-			gettextln "Cannot rebase: You have unstaged changes." >&2
-			;;
 		"rewrite branches")
 			gettextln "Cannot rewrite branches: You have unstaged changes." >&2
 			;;
@@ -235,14 +232,7 @@
 		if test $err = 0
 		then
 			action=$1
-			case "$action" in
-			rebase)
-				gettextln "Cannot rebase: Your index contains uncommitted changes." >&2
-				;;
-			*)
-				eval_gettextln "Cannot \$action: Your index contains uncommitted changes." >&2
-				;;
-			esac
+			eval_gettextln "Cannot \$action: Your index contains uncommitted changes." >&2
 		else
 		    gettextln "Additionally, your index contains uncommitted changes." >&2
 		fi