Bug in allout-hide-current-leaves

[martin rudalics <rudalics@gmx.at>]

To reproduce with Emacs -Q: Open src/keyboard.c, do M-x allout-mode, and
M-x allout-hide-current-leaves.  Gets me:

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
   -(nil nil 2)
   (max 1 (- allout-recent-prefix-end allout-recent-prefix-beginning allout-header-subtraction))
   (setq allout-recent-prefix-end (or (match-end 1) (match-end 2)) allout-recent-prefix-beginning (or (match-beginning 1) (match-beginning 2)) allout-recent-depth (max 1 (- allout-recent-prefix-end allout-recent-prefix-beginning 
allout-header-subtraction)))
   allout-prefix-data()
   (setq done (allout-prefix-data))
   (if (looking-at allout-regexp) (setq done (allout-prefix-data)) (forward-char -1))
   (while (and (not done) (search-backward "\n" nil 1)) (forward-char 1) (if (looking-at allout-regexp) (setq done ...) (forward-char -1)))
   (let (done) (while (and ... ...) (forward-char 1) (if ... ... ...)) (if (bobp) (cond ... ... ...) done))
   (progn (let (done) (while ... ... ...) (if ... ... done)))
   (unwind-protect (progn (let ... ... ...)) (set-match-data save-match-data-internal (quote evaporate)))
   (let ((save-match-data-internal ...)) (unwind-protect (progn ...) (set-match-data save-match-data-internal ...)))
   (save-match-data (let (done) (while ... ... ...) (if ... ... done)))
   allout-goto-prefix()
   (if (allout-goto-prefix) (if (and ... ...) (allout-previous-heading) (point)))
   allout-goto-prefix-doublechecked()
   (if (allout-goto-prefix-doublechecked) (if (<= ... bol-point) (if ... ... ...) (goto-char ...) nil))
   (let ((bol-point ...)) (if (allout-goto-prefix-doublechecked) (if ... ... ... nil)))
   allout-back-to-current-heading()
   allout-hide-current-leaves()
   call-interactively(allout-hide-current-leaves)
   execute-extended-command(nil)
   call-interactively(execute-extended-command)

Note that `allout-regexp' is

"\\(/\\*_[ 	]*[\\.,\\*\\+--=>()\\[{}&!\\?#%\"X@\\$~_\\\\:;\\^/\\*_]\\)\\|\\(/\\*_\\|/\\*_\\)+ ?[^/*_]\\|\f"

hence it cannot possibly match _two_ parenthetical subexpressions.