bug#41941: Signing git commits with PGP fails

[Leo Famulari]

On Fri, Jun 19, 2020 at 12:35:09AM +0200, Jonathan Brielmaier wrote:
> I have a strange error/problem with signing git commits with PGP.

The setup can be complicated...

> Following situation
> 
> `git` is installed via system configuration
> `git:send-email` via `guix install` into the user profile
> 
> ~/.gitconfig has
> ```
> [commit]
>   gpgsign = true
> ```

I also have:

------
[gpg]
        program = gpg 
[user]
        signingkey = B0515948F1E7D3C1B98038A02646FA30BACA7F08
------

> but trying to sign a git commit fails:
> ```
> git commit -m "test"
> error: gpg failed to sign the data
> fatal: failed to write commit object
> ```

Do you also have a GPG pinentry program installed? Are you able to sign
an arbitrary file with GPG, outside of Git? For example:

$ gpg --output test.sig --sign file