bug#26761: 25.1; Emacs freezes when scrolling with mouse wheel

[Christoph Groth <christoph@grothesque.org>]

I compiled Emacs from current git.  Unfortunately, the only way 
that I know to reproduce the freeze is when viewing a particular 
message with Gnus.  That's why I need to run Emacs with my full 
configuration.

When I start the newly compiled Emacs, it complains about the use 
of "some" in my init.el:
Symbol's function definition is void: some

So I comment-out this bit since it's not relevant.

Then, when I try to launch Gnus, it complains about my ~/.gnus:

gnus-read-init-file: Error in ~/.gnus: (lambda (name &optional 
lists &optional extra-split-methods-before &optional 
extra-split-methods-after &optional extra-vars) (append (list 
(quote nnimap) name (quote (nnimap-stream shell)) (quote 
(nnimap-unsplittable-articles (%Deleted))) (list (quote 
nnimap-shell-program) (format my-nnimap-shell-program name)) (list 
(quote nnimap-split-methods) (append extra-split-methods-before 
(mapcar (function (lambda (name) (list name (format ^list-id: 
.*<%s\. name)))) lists) extra-split-methods-after))) extra-vars))

This is probably related to the following code in my ~/.gnus:

(defun my-nnimap-configure (name
                            &optional lists
                            &optional extra-split-methods-before
                            &optional extra-split-methods-after
                            &optional extra-vars)
  (append
   `(nnimap ,name
            (nnimap-stream shell)
            (nnimap-unsplittable-articles (%Deleted))
            (nnimap-shell-program ,(format my-nnimap-shell-program 
            name))
            (nnimap-split-methods
             ,(append extra-split-methods-before
                      (mapcar
                       (lambda (name)
                         (list name (format "^list-id: .*<%s\\." 
                         name)))
                       lists)
                      extra-split-methods-after)))
   extra-vars))

(setq gnus-secondary-select-methods
      (list (my-nnimap-configure
             "aaa"
             '("list1" "list2"
               "list3" "list4"
               "list5" "list6"
               "list7" "list8")
             '(("something" "^From: .*@something.org")
               ("other-thing" "^Subject: .*other.*thing"))
             my-nnimap-final-split-methods
             '((nnimap-inbox ("INBOX" "Sent"))))
            (my-nnimap-configure
             "bbb"
             '("list9")
             nil
             (append
              '(("mangled-own" my-mangled-own-p))
              my-nnimap-final-split-methods)
             '((nnimap-inbox ("INBOX" "Sent Items"))))
            (my-nnimap-configure "old")))

I wrote the function my-nnimap-configure to simplify the creation 
of the gnus-secondary-select-methods variable.  It works with 
emacs 24 and 25 as found in Debian.  I do not know what's the 
problem with it when used with bleeding-edge Emacs.