Make wiki default branch name changable (#29603)

Fix #29000
Fix #28685
Fix #18568

Related: #27497

And by the way fix #24036, add a Cancel button there (one line)

models/migrations/migrations.go

@@ -562,6 +562,8 @@ var migrations = []Migration{
 	NewMigration("Use Slug instead of ID for Badges", v1_22.UseSlugInsteadOfIDForBadges),
 	// v288 -> v289
 	NewMigration("Add user_blocking table", v1_22.AddUserBlockingTable),
+	// v289 -> v290
+	NewMigration("Add default_wiki_branch to repository table", v1_22.AddDefaultWikiBranch),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_22/v289.go

@@ -0,0 +1,18 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_22 //nolint
+
+import "xorm.io/xorm"
+
+func AddDefaultWikiBranch(x *xorm.Engine) error {
+	type Repository struct {
+		ID                int64
+		DefaultWikiBranch string
+	}
+	if err := x.Sync(&Repository{}); err != nil {
+		return err
+	}
+	_, err := x.Exec("UPDATE `repository` SET default_wiki_branch = 'master' WHERE (default_wiki_branch IS NULL) OR (default_wiki_branch = '')")
+	return err
+}