erc-button-remove-old-buttons
erc-button-remove-old-buttons is a compiled Lisp function in `erc-button.el
'.
(erc-button-remove-old-buttons)
Remove all existing buttons.
This is called with narrowing in effect, just before the text is
buttonized again. Removing a button means to remove all the properties
that `erc-button-add-button' adds, except for the face.