git push fails but works fine with "git push"

**Describe the bug**
I was trying to push and it fails says it can't find the URL to the git server. If I just go to my terminal and do a "git push" it works fine.

**To Reproduce**
Steps to reproduce the behavior:
1. My git server is working through a vpn so I imagine you would need to first set up a vpn to test gitui is able to push normally.
2. open gitui and do a git push
3. See error

**Expected behavior**
It should use the same functionality as a normal "git push" to avoid having to set things up in another way.

**Context (please complete the following information):**
- Latest gitui from Arch repos version 0.25.1

まず、Git サーバーに VPN 経由で接続できる状態で gitui 0.25.1 の失敗を再現し、その後、ターミナルで成功する `git push` と比較します。gitui がサーバー URL を見つけられない理由を調査します。同じ設定で通常の Git コマンドを使う場合と同様に、gitui 経由の push が機能すれば完了です。

索引モデルが issue の本文から書いたものです。