Invoking `erc-log-save-all-buffers' periodically

Hello,

I wanted to have something like that:

  ;; Save IRC logs periodically when we're idle.
  (run-with-idle-timer 180 t 'erc-log-save-all-buffers)

However, it turns out that `erc-current-logfile', called indirectly by
`erc-log-save-all-buffers', uses nil as the SERVER value, which makes
`erc-generate-log-file-name-long' return a bogus file name.

This is with ERC Version 5.3 (GNU Emacs 23.0.90.1).  Any idea?

Thanks,
Ludo'.