before-change-functions called twice at yank

[Lars Hansen]

Do emacs -q and evaluate

(progn
  (add-hook 'before-change-functions
            (lambda (b e)
              (message "before-change: '%s'" (buffer-substring b e))) nil t)
  (add-hook 'after-change-functions
            (lambda (b e l)
              (message "after-change: '%s'" (buffer-substring b e))) nil t))


in the *scratch* buffer. If you press the letter a, the message buffer
will get

before-change: ''
after-change: 'a'

as expected. Now yank the string "foo". Then the message buffer gets

before-change: ''
after-change: 'foo'
before-change: 'foo'

This seems as a bug to me. Am I missing something?