Honor delete branch on merge repo setting when using merge API (#35488)

Fix #35463.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/util/error_test.go

@@ -0,0 +1,29 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package util
+
+import (
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorTranslatable(t *testing.T) {
+	var err error
+
+	err = ErrorWrapTranslatable(io.EOF, "key", 1)
+	assert.ErrorIs(t, err, io.EOF)
+	assert.Equal(t, "EOF", err.Error())
+	assert.Equal(t, "key", err.(*errorTranslatableWrapper).trKey)
+	assert.Equal(t, []any{1}, err.(*errorTranslatableWrapper).trArgs)
+
+	err = ErrorWrap(err, "new msg %d", 100)
+	assert.ErrorIs(t, err, io.EOF)
+	assert.Equal(t, "new msg 100", err.Error())
+
+	errTr := ErrorAsTranslatable(err)
+	assert.Equal(t, "EOF", errTr.Error())
+	assert.Equal(t, "key", errTr.(*errorTranslatableWrapper).trKey)
+}