setup creates new branch in existing store

[leogott]

Summary

When I installed gopass on a new system, I tried to follow proper procedure for once, and wanted to set it up with a new dedicated gpg key. The setup script unexpectedly created a new empty master branch in my pw-store repository, and pushed the public key there.
This probably happened, because the OS-included version of git inits new repositories with a master-branch, and I hadn't yet configured git config --global init.defaultBranch main, (but I didn't verify whether the issue would occur, had I done that beforehand).

Managed to fix it, but some trial and error was involved.

I forgot to report this bug on the day… I hope my missive is accurate enough.

Steps To Reproduce

0. have an existing pw-store git-repo with a single (default-)branch that is not named master or what your git init.defaultBranch is set to
1. run gopass setup with this repo
2. ???
3. profit

Expected behavior

gopass setup should clone the existing branch (and/or ask which branch to use and whether to create a new empty branch)

Environment

• OS: Pop!OS (based on ubuntu)
• OS version: 22.04 LTS
• gopass Version: v1.15.11, I think
• Installation method: github release

Additional context