Subkeys suffixed with `!` are resolved to their primary key

This makes adding two encryption subkeys from the same primary key impossible.
The reason for doing this is because I have two yubikeys, each owning one of the subkeys, and I'd like to be able to unlock the repositories with either. [password-store][1] allows me to do this.

I'm not familiar myself with the gpg internals either in git-crypt nor in password-store, so I'm kindly asking someone to tell me which debug output would be helpful to resolve this issue.

[1]: https://www.passwordstore.org/