500 error when reopening an Agit PR

[Infinoid]

Description

Some of our users get a bit lost when we start talking about branches and forks; they use the Agit syntax to submit PRs. This mostly works.

When an Agit-submitted PR is closed, and then the "Reopen" button is pressed, the server responds with a 500 internal server error.

Ideally it would not return a 500 error; it would either reopen the PR, or (more likely) provide a clear error message about the temporary branch being deleted (or whatever).

I included a log from our production instance from when we first noticed this problem. It's quite short.

Reproducer

First, make a git repo. I called mine "test". Add a file, commit it, push it to the server.

% git init
Initialized empty Git repository in .../test/.git/
% echo test >test
% git add test
% git commit
[main (root-commit) c842de3] test
 1 file changed, 1 insertion(+)
 create mode 100644 test
% git remote add origin https://try.gitea.io/infinoid/test-agit.git
% git push -u origin main
Enumerating objects: 3, done.
Counting objects: 100% (3/3), done.
Writing objects: 100% (3/3), 207 bytes | 207.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
remote: . Processing 1 references
remote: Processed 1 references in total
To https://try.gitea.io/infinoid/test-agit.git
 * [new branch]      main -> main
branch 'main' set up to track 'origin/main'.
% 

Next, add a second commit, and submit it using Agit syntax.

% echo test2 > test2
% git add test2
% git commit
[main f6c5761] test2
 1 file changed, 1 insertion(+)
 create mode 100644 test2
% git push origin HEAD:refs/for/main -o topic=test2 -o title=test2 -o description=test2
Enumerating objects: 4, done.
Counting objects: 100% (4/4), done.
Delta compression using up to 64 threads
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 263 bytes | 263.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
remote: 
remote: Visit the existing pull request:
remote:   https://try.gitea.io/infinoid/test-agit/pulls/1
remote: 
remote: . Processing 1 references
remote: Processed 1 references in total
To https://try.gitea.io/infinoid/test-agit.git
 * [new reference]   HEAD -> refs/pull/1/head
% 

Click on the link to the new PR (number 1 in my test repo).
Click the Close button.
Click the Reopen button.
Bam, 500 error.

Gitea Version

1.20.2, 1.21.0+dev-463-g6a7a5ea32 (the version of try.gitea.io at time of writing)

Can you reproduce the bug on the Gitea demo site?

Yes

Log Gist

https://gist.github.com/Infinoid/65cf9fb54e87a8cb3acd83dccee7e7d5

Screenshots

Git Version

No response

Operating System

No response

How are you running Gitea?

I was able to reproduce this problem on try.gitea.io.

Database

None

[lunny]

@a1012112796 could you help to take a look at?