It can be confusing that some commits (typically the working copy)
don't have a description. Let's show a placeholder text in such cases.
I chose the format to match the "(no email configured)" message we
already have.
Our support for aliases is very naively implemented; it assumes the
alias is the first argument in argv. It therefore fails to resolve
aliases after global arguments such as `--at-op`.
This patch fixes that by modifying the command defintion to have an
"external subcommand" in the list of available commands. That makes
`clap` give us the remainder of the arguments when it runs into an
unknown command. The first in the list will then be an alias or simply
an unknown command. Thanks to @epage for the suggestion on in
clap-rs/clap#3672.
With the new structure, it was easy to handle recursive alias
definitions, so I added support for that too.
Closes#292.
