Re: [PATCH 4/5] ref-filter: truncate atom names in error messages

> It seems like the cleanest fix would be for atom->name to be _just_ the
> name, since there's already a separate "args" field. But since that
> field is also used for other things, we can't change it easily (e.g.,
> it's how we find things in the used_atoms array, and clearly %(refname)
> and %(refname:short) are not the same thing).
>
> Instead, we'll teach our error_bad_arg() function to stop at the first
> ":". This is a little hacky, as we're effectively re-parsing the name,
> but the format is simple enough to do this as a one-liner, and this
> localizes the change to the error-reporting code.
>
> We'll give the same treatment to err_no_arg(). None of its callers use
> this atom->name trick, but it's worth future-proofing it while we're
> here.