Tentative to reattach timestamps from ZNC correctly

erc.conf.el

;; ZNC will replay a buffer and prefix each message with a
;; timestamp. Let's extract this timestamp and redefine current-time
;; to make them appear as regular timestamp. We use an advice to be
;; able to locally define `current-time` function.
(defadvice erc-add-timestamp (around vbe/erc-add-timestamp)
  "Extract timestamp beginning a message and display it like a regular timestamp"
  (save-match-data
    (goto-char (point-min))
    (if (looking-at "^\\s-*\\S-+ \\[\\([0-9][0-9]\\):\\([0-9][0-9]\\):\\([0-9][0-9]\\)\\] ")
        (let ((hours (match-string 1))
              (minutes (match-string 2))
              (seconds (match-string 3))
              (start (- (match-beginning 1) 1))
              (end (+ (match-end 3) 2)))
          (delete-region start end)
          (cl-flet ((current-time ()
                                  (list 0
                                        (+ (* (string-to-number hours) 3600)
                                           (* (string-to-number minutes) 60)
                                           (string-to-number seconds))
                                        0
                                        0)))
            ad-do-it))
          ad-do-it)))
(ad-activate 'erc-add-timestamp)