[InterNetNews/inn] 9b37fa: Add a special comment in response to MAXARTNUM

[Julien ÉLIE]

  Branch: refs/heads/2.7
  Home:   https://github.com/InterNetNews/inn
  Commit: 9b37faffc380bc0c2625ccb3bc507215c8f0100e
      https://github.com/InterNetNews/inn/commit/9b37faffc380bc0c2625ccb3bc507215c8f0100e
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-01-24 (Tue, 24 Jan 2023)

  Changed paths:
    M innd/nc.c
    M nnrpd/nnrpd.c

  Log Message:
  -----------
  Add a special comment in response to MAXARTNUM

As INN does not handle article numbers greater than 2^31-1, there's no
point in implementing the MAXARTNUM command.  Just return 500 but with
a special comment mentioning our 2^31-1 limit.