Error when running gren init

When I run gren init, I get the following message:
```
$ gren init
You have to run this command in a git repo folder
```

However, this *is* a git repo folder, i.e. it has a .git subdirectory.

Unfortunately, there is no further information what might be wrong. Any suggestions?

首先，在包含 `.git` 目录的 Git 仓库中重现 `gren init`，然后跟踪该命令使用的仓库检测路径。完成的标准是：命令能够正确处理有效仓库，或报告其无法继续的实际原因；payload 未指定要运行的文件或测试。

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