alertnotify: how long is long?

Question

  -alertnotify=<cmd>
       Execute command when a relevant alert is received or we see a really
       long fork (%s in cmd is replaced by message)

How long is "a really long fork"?

Answer 1

1. -alertnotify is only used by validation.cpp::AlertNotify
2. validation.cpp::AlertNotify is only used by validation.cpp::DoWarning
3. validation.cpp::DoWarning is only used by validation.cpp::CChainState::UpdateTip, for rules, not for forks or for alerts.

Because 1. and 2. and 3., there is no "long" at all. The RPC command help is obsolete.