Fix http protocol auth (#27875) (#27876)

Backport #27875 by @lunny

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/web/repo/githttp_test.go

@@ -0,0 +1,42 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestContainsParentDirectorySeparator(t *testing.T) {
+	tests := []struct {
+		v string
+		b bool
+	}{
+		{
+			v: `user2/repo1/info/refs`,
+			b: false,
+		},
+		{
+			v: `user2/repo1/HEAD`,
+			b: false,
+		},
+		{
+			v: `user2/repo1/some.../strange_file...mp3`,
+			b: false,
+		},
+		{
+			v: `user2/repo1/../../custom/conf/app.ini`,
+			b: true,
+		},
+		{
+			v: `user2/repo1/objects/info/..\..\..\..\custom\conf\app.ini`,
+			b: true,
+		},
+	}
+
+	for i := range tests {
+		assert.EqualValues(t, tests[i].b, containsParentDirectorySeparator(tests[i].v))
+	}
+}