It can:
* Parse the `~/.git-coauthors` file
* List available co-authors with --list
* Filter available co-authors given a list of initials, giving an error
if no co-author matches a given initial
`git-solo` clears the `.git/.gitmessage` commit message template in the
current git repository.
If the current working directory is not within a git repository, it will
print `Not in a git repository` on stderr and exit.