Reuse client cert for connectivity probing in ERC

* lisp/erc/erc-backend.el (erc--server-connect-function)
(erc--server-post-dial-function): Rename former to latter because the
existing name is better suited for the eventual generalizing of
`erc-server-connect' in a future version.
(erc-server-connect): Use new name for `erc--server-connect-function',
`erc--server-post-dial-function'.
(erc--recon-probe-reschedule, erc--recon-probe-sentinel)
(erc--recon-probe-filter, erc--recon-probe-check): New functions
factored out of `erc-server-delayed-check-reconnect'.
(erc-server-delayed-check-reconnect): Refactor, splitting off lambdas
into top-level functions for improved tracing.
* lisp/erc/erc.el (erc-message-english-recon-probe-hung-up)
(erc-message-english-recon-probe-nobody-home): New
variables.  (Bug#62044)

Thanks to Libera.Chat user arjan for reporting this bug, which
is new in ERC 5.6 and Emacs 30.1.

1 files changed, 2 insertions, 0 deletions

diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 28ccb5809a7..72335a444cb 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -9572,6 +9572,8 @@ SOFTP, only do so when defined as a variable."
    (ignore-list . "%-8p %s")
    (reconnecting . "Reconnecting in %ms: attempt %i/%n ...")
    (reconnect-canceled . "Canceled %u reconnect timer with %cs to go...")
+   (recon-probe-hung-up . "Server answered but hung up. Delaying by %ts...")
+   (recon-probe-nobody-home . "Nobody home...")
    (finished . "\n\n*** ERC finished ***\n")
    (terminated . "\n\n*** ERC terminated: %e\n")
    (login . "Logging in as `%n'...")