bug#50007: 28.0.50; normalize logic surrounding erc-server-reconnecting

[Stefan Kangas]

"J.P." <jp@neverwas.me> writes:

> Tags: patch
>
> Knowing when we're reconnecting and having that logic be as sane and
> straightforward as possible is (IMO) a critical component of unraveling
> the buffer-association game I've been trying to drag everyone into.
>
> The existing approach is troublesome because it's basically inscrutable
> in the sense of being too difficult to sit down and reason through once
> session identities enter the fray (at least for a simpleton like me).
> And though the solution I'm proposing may seem underwhelming, it wasn't
> just intuited out of thin air but rather discovered with the backing of
> behavioral tests like the ones included in these patches [1]. Thanks.
>
>
> [1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48598
>     https://debbugs.gnu.org/cgi/bugreport.cgi?bug=49860

Copying in the ERC maintainer Amin Bandali here.

Amin, could you help review this patch?