bug#28597: 26.0.60; [Security] Configure should use --without-pop by default

[N. Jackson]

At 16:20 -0700 on Monday 2017-10-02, Paul Eggert wrote:
>
> On 10/02/2017 11:47 AM, Eli Zaretskii wrote:
>
>> nagging users each time they invoke movemail to fetch via POP3
>> is IMO unacceptable.
>
> Yes, that suggestion is problematic.

Just for the record, I explicitly stated in my suggestion to warm
the user (rather than just the builder) that Emacs should _not_ nag
the user every time.

I was thinking of disabling the commands in question in the case
that they will be insecure and prompting along the lines of:

  You have typed abc, invoking disabled command xyz.

  Beware: This command retrieves POP3 email via only insecure
  channels. See [reference to relevant documentation] for more
  information.

  Do you want to use this command anyway?

  You can now type
  y   to try it and enable it (no questions if you use it again).
  n   to cancel--don't try the command, and it remains disabled.
  SPC to try the command just this once, but leave it disabled.
  !   to try it, and enable all disabled commands for this session only.

This informs the user but only does so once (if they don't want to
be told again); after that they need not see the warning ever
again. Telling someone something once really cannot be described
as "nagging".

N.