bug#30056: 25.3; battery-mode-line-string missing leading space

[Eli Zaretskii <eliz@gnu.org>]

> From: Allen Li <vianchielfaura@gmail.com>
> Date: Wed, 10 Jan 2018 15:26:42 -0800
> Cc: Glenn Morris <rgm@gnu.org>, 30056@debbugs.gnu.org
> 
> >> See also https://debbugs.gnu.org/18164
> >
> > We don't do this consistently in the modes which use
> > global-mode-string: some of them leave a blank at the beginning,
> > others (the majority, AFACT) don't.  There's not much space on the
> > mode line, so I'm not sure which way is better.
> 
> The standard for minor mode strings is to include a leading space, right?

That's just it: I'm not sure.

> In any case, Emacs packages should probably be consistent, and
> currently display-battery-mode and display-time-mode are inconsistent.
> I don’t know which other modes use global-mode-string; is display-time
> mode the only outlier?

Not at all: grep for that variable in the Emacs source tree, and you
will see that most of its users don't start their strings with a
blank.  Which is why I asked this question:

> > But if we want to have a separation there, would it make sense to do
> > this in bindings.el, so that global-mode-string is always separated by
> > a blank from the preceding text, and modes don't have to remember this
> > gork?