Auto expand "New PR" form

[wxiaoguang]

Follow GitHub's behavior: use ?expand=1 to expand the "New PR" form

The old .Flash check is not needed anymore because now we use "fetch action form", no flash message.

[wxiaoguang]

[silverwind]

Will this also work for the links that are output when pushing to a new branch over SSH? GitHub uses a special URL scheme like repo/pulls/new/branch which redirects to a auto-expanded compare page. I think it's using a ?-less URL so its easier to copy from terminal.

I would strongly prefer if we have that URL too and it could be used for this "Open PR" button.

[wxiaoguang]

Will this also work for the links that are output when pushing to a new branch over SSH?

I do not know where it is (I don't use it).

So feel free to add it in this PR or improve it in the future.

[silverwind]

Will this also work for the links that are output when pushing to a new branch over SSH?

I do not know where it is (I don't use it).

So feel free to add it in this PR or improve it in the future.

It's the message that shows for the first time when pushing to a branch:

$ git checkout -b test
branch 'test' set up to track 'master' by rebasing.
Switched to a new branch 'test'
$ git commit --allow-empty -m 'test'
[test 3bbb14a] test
$ git push origin test
Enumerating objects: 1, done.
Counting objects: 100% (1/1), done.
Writing objects: 100% (1/1), 367 bytes | 183.00 KiB/s, done.
Total 1 (delta 0), reused 0 (delta 0), pack-reused 0 (from 0)
remote:
remote: Create a new pull request for 'test':
remote:   https://gitea.com/org/repo/compare/master...test  <----
remote:
remote: . Processing 1 references
remote: Processed 1 references in total
To gitea.com:org/repo.git
 * [new branch]      test -> test

[silverwind]

FYI, here is the same link that GitHub produces:

remote:
remote: Create a pull request for 'test2' on GitHub by visiting:
remote:      https://github.com/silverwind/gitea/pull/new/test2
remote:

When opening the link https://github.com/silverwind/gitea/pull/new/test2, it redirects to https://github.com/go-gitea/gitea/compare/main...silverwind:gitea:test2?expand=1, e.g. the expanded compare page.

[wxiaoguang]

When opening the link https://github.com/silverwind/gitea/pull/new/test2, it redirects to https://github.com/go-gitea/gitea/compare/main...silverwind:gitea:test2?expand=1, e.g. the expanded compare page.

f1b1264

[silverwind]

Awesome work, thanks