Cannot fetch unless a remote is defined

Hi,

Thank you for pygit2! I'm using it extensively for git tooling in Ubuntu, but occasionally I find some corner where a feature doesn't exist and I have to resort to calling a git subprocess.

The git CLI allows me to use git fetch without having a remote defined. I can just specify a URL. I can't find any documentation on this in pygit2 though. It looks like I have to define a remote, with a name, first. Since I don't necessarily own the repository, this requires an ugly workaround because I have to be concerned about name collisions, crashing without having removed a temporary remote, etc.

Any chance of adding API functionality to fetch (and presumably) push against remotes with just a URL and no mandatory repository configuration please?

まず、issue で説明されている git CLI の動作と併せて、pygit2 に既に存在する remote 定義および fetch/push のエントリーポイントを確認します。名前付き remote を作成せずに URL のみで fetch と push を実行する方法を明らかにし、その後、対象を絞ったテストで動作を検証します。両方の操作がリポジトリ設定を必要とせずに URL を受け付ければ完了です。