bug#50965: Allow nil third argument for mapconcat

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> Please consider allowing an empty third argument for mapconcat that
> means the empty string, i.e.:
>
>     (mapconcat FUNCTION SEQUENCE SEPARATOR)
>
> Becomes:
>
>     (mapconcat FUNCTION SEQUENCE &optional SEPARATOR)

I think that makes sense -- SEPARATOR is optional in the related

(string-join strings &optional separator)

function.

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