DefaultBranch is not set correctly when using template which has 'master' as default

[sschroe]

Description

In #19354 the default branch for new repositories was changed from 'master' to 'main'. When running this new version on existing data where 'master' was still used as default this causes a problem when creating a new repository from a template which still uses 'master'.

The files and master branch are correctly copied to the newly generated repository however giteas internal default branch is set to 'main' instead of 'master'. This causes giteas "Branches" page to remain blank despite showing 1 branch and when cloning the repository git shows warning: remote HEAD refers to nonexistent ref, unable to checkout..

When opening the "Branches" page gitea throws an error: 2022/04/23 10:48:22 ...s/web/repo/branch.go:177:loadBranches() [W] [6263bd56] loadBranches: missing default branch main for 60:sschroe/template_test

Example of a broken repo on the demo site: https://try.gitea.io/steffen/template_test/branches

To reproduce:

• Run gitea with the default config
• Create a new template repository and set its main branch to 'master'
• Create a new repository and select the previously made template with "Git Content(Default Branch)" checked
• Open the "Branches" page on the new repository

Gitea Version

9550e5a

Can you reproduce the bug on the Gitea demo site?

Yes

Log Gist

No response

Screenshots

No response

Git Version

2.36.0

Operating System

Arch Linux

How are you running Gitea?

git clone': git clone --recursive https://github.com/go-gitea/gitea.git
cd gitea
TAGS="bindata sqlite sqlite_unlock_notify" make build
./gitea

Database

SQLite

[wxiaoguang]

You should update your templates at the moment, or set global default branch back to master. Otherwise Gitea can not guess what's the correct main branch.

For example, even before #19354 , if you create a template repo with main as default branch while global default branch is master, then the same thing happens.

The blank branches page could be another bug. Indeed all branches should be shown correctly even if the default branch is incorrect.

One possible way to improve the behavior is to make Gitea use the only (or latest) branch in template as the default branch for the newly created repo if the default branch name doesn't match.