Lack of debug info from git commit -vvv -S -am "..."

[Jeffrey Walton <noloader@xxxxxxxxx>]

I'm trying to determine why a new installation of GnuPG is having
trouble. The new install is in /usr/local. The other install is from
the distro and is OK.

Here's the new installation error message:

    $ git commit -vvv -S -am "Update GnuPG recipe"
    error: gpg failed to sign the data
    fatal: failed to write commit object

How can I obtain more information from git commit?