[BUG] Footnotes break iCalendar export [9.4.6 (9.4.6-g069bcb @ /home/msi/.emacs.d/straight/build/org/)]

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Hello,

I have some footnotes in my Org agenda files.
So I want to export my org agenda with this : 
org-icalendar-combine-agenda-files. Without footnotes, I don't have any
problem. But with, I have this in my .ics file.

SUMMARY:Hello
DESCRIPTION:<2012-04-20 Sat 15:00>
CATEGORIES:test
END:VEVENT



Footnotes
─────────

[1] which isn't very interesting

[2] which still isn't very interesting
END:VCALENDAR


It's, I think, the same problem of this thread :

https://lists.gnu.org/archive/html/emacs-orgmode/2013-04/msg01478.html

I try to add this :

(footnote-definition . ignore)

in

ox-ascii.el.

But, it doesn't works :/.

Thank you in advance.




Emacs  : GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, 
cairo version 1.16.0)
 of 2020-09-19
Package: Org mode version 9.4.6 (9.4.6-g069bcb @ 
/home/msi/.emacs.d/straight/build/org/)