This is a workaround for command name completion. On zsh, the complete position
is specified by $_CLAP_COMPLETE_INDEX, and an empty argument isn't padded. So,
for "jj <TAB>", { args = ["jj"], index = 1 } is provided, and our expand_args()
helpfully fills in the default command "log". Since args[index] is now "log",
no other commands are listed.
This makes completions suggest aliases from the user or repository
configuration. It's more useful for long aliases that aren't used very often,
but serve the purpose of "executable documentation" of complex and useful jj
commands.
An earlier patch "resolved" aliases, meaning that any arguments following an
alias would be completed as if the normal command had been used. So it only
made sure that using aliases doesn't degrade the rest of the completions.
Commit ID: 325402dc94
