bug#35756: [PATCH] file-size-human-readable: fix glitches and add optional space

[Eli Zaretskii <eliz@gnu.org>]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Wed, 15 May 2019 22:02:50 +0200
> 
> The `file-size-human-readable' function is very useful but could do with some better formatting: normally, a space goes between the number and unit; you don't write '3kg' or '25m/s' but '3 kg' and '25 m/s' (sloppy British newspapers notwithstanding). We could add an optional argument so that the caller can use the spacing of preference; the default should probably be no space, for compatibility.

I have no opinion regarding the change, but I have a minor comment
about the documentation:

> +** The function 'file-size-human-readable' accepts another optional argument.
> +The new third argument is a string put between the number and unit;
> +if nil or omitted, the empty string is used.  It is recommended to use
> +a single space or non-breaking space for readability.

This uses the passive tense too much.  The "if nil or omitted, the
empty string is used" part could be worded more clearly as "it
defaults to the empty string".  The "It is recommended" part is better
worded as "We recommend".

> +Optional third argument SPACE is a string put between the number and unit.
> +If nil or omitted, the empty string is used.

Same here.

Thanks.