[InterNetNews/inn] cec375: pullnews: Gracefully handle socket timeout

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: cec3759be8ae51cfd2a6de6a3ef86442bdea1bfe
      https://github.com/InterNetNews/inn/commit/cec3759be8ae51cfd2a6de6a3ef86442bdea1bfe
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-01-23 (Mon, 23 Jan 2023)

  Changed paths:
    M doc/pod/news.pod
    M doc/pod/pullnews.pod
    M frontends/pullnews.in

  Log Message:
  -----------
  pullnews: Gracefully handle socket timeout

pullnews goes on downloading articles one by one from a remote news
server even though the connection was stopped for whatever reason.  It
now checks for that, and makes re-attempts according to the -T setting.

Net::NNTP returns a 421 (sic) pseudo response code when a connection is no
longer active; that's what pullnews checks for.

Thanks to Jesse Rehmer for the bug report.

close #239