First commit weirdness

**Describe the bug**

Using `gitui` to make the first commit in a repository doesn't work, and somehow changes the active branch to `master` (this is not `init.defaultbranch` either, mine is set to `main`)

**To Reproduce**

Steps to reproduce the behavior:
1. Create a blank repository
2. Make a commit
3. Observe that it didn't commit anything
4. Open the `Branches` menu
5. The active branch has changed to `master`
6. `git branch` by now lists only the `master` branch, but it's not active

**Expected behavior**

The commit should have succeeded, and the active branch should not have been changed.

**Screenshots**

Here's an asciinema replay:

https://asciinema.org/a/K8Cu0yDaRTbjROPn9SCwRM6LD

**Context (please complete the following information):**

According to `gitui --bugreport` (env vars and command line omitted):

```
#### Software version

gitui 0.27.0

#### Operating system

- OS: Linux (Fedora Linux 42)
- Kernel: 6.15.8-200.fc42.x86_64

#### Compile time information

- Profile: release
- Target triple: x86_64-unknown-linux-gnu
- Family: unix
- OS: linux
- Architecture: x86_64
- Pointer width: 64
- Endian: little
- CPU features: fxsr,sse,sse2,x87
- Host: x86_64-unknown-linux-gnu
```

**Additional context**
Add any other context about the problem here.

Reproduziere das Problem in einem leeren Repository anhand der gemeldeten Schritte und verfolge anschließend den Ablauf des ersten Commits sowie das Menü Branches, in dem der aktive Branch zu master wechselt. Als abgeschlossen gilt die Aufgabe, wenn der initiale Commit erfolgreich ist, der konfigurierte Standard-Branch aktiv bleibt und die Branch-Liste diesen Branch widerspiegelt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.