Auto-cloning a Gitlab repo fails with "unable to update url base from redirection"

### Background

My organisation is exploring Coder with the Backstage plugin and Gitlab.com (Gitlab SaaS, i.e. not self-hosted).

In Backstage, before creating anything, the plugin shows:

> No workspaces found for repo
> https://gitlab.com/myorg/myrepo/-/blob/main/?ref_type=heads

We see #117 and the fact a change was made, and also that a merge was made to the git clone module in PR [210](https://github.com/coder/modules/pull/210#issue-2217313475), but we are yet to be able to make it work.

### Challenge

With a template that auto-clones, for example using the `git_clone` module:

```hcl
data "coder_parameter" "repo_url" {
name = "repo_url"
display_name = "Git repository"
}

module "git_clone" {
source = "registry.coder.com/modules/git-clone/coder"
version = "1.0.18"
agent_id = coder_agent.main.id
url = data.coder_parameter.repo_url.value
}
```

We see the clone fail after redirection:

```
Cloning https://gitlab.com/myorg/myrepo/-/blob/main/ to /home/coder/main...
Cloning into '/home/coder/main'...

fatal: unable to update url base from redirection:
asked for: https://gitlab.com/myorg/myrepo/-/blob/main/info/refs?service=git-upload-pack
redirect: https://gitlab.com/groups/myorg/-/saml/sso?redirect=%2Fmyorg%2Fmyrepo%2F-%2Fblob%2Fmain%2Finfo%2Frefs%3Fservice%3Dgit-upload-pack&token=
```

We enforce single sign-on, which may explain the saml/sso redirection.

### Alternatives

If we do not "auto-clone", and instead try and clone from the Workspace template directly (providing "Git repository" in the GUI), providing "https://gitlab.com/myorg/myrepo", then it works.

The downside is that the Backstage plugin won't "match" the Workspace as being related to the Backstage entity (presumably because we omitted the `-/blob/main/?ref_type=heads` suffix).

Has anyone been able to make this work with Gitlab yet please?

Bắt đầu với plugin Backstage và module git_clone được tham chiếu trong template; trước tiên hãy xem lại issue #117 và PR 210. Tái hiện bằng URL GitLab kết thúc bằng /-/blob/main/?ref_type=heads và so sánh với URL thư mục gốc của repository đang hoạt động. Hoàn tất khi tự động clone thành công với GitLab SAML SSO và workspace vẫn khớp với Backstage entity.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.