Strange contents on some ftp mirrors

[Marcin Wisnicki]

At this very moment, french package mirror has INDEX newer than in
other mirrors:

> fetch -o INDEX-xx.bz2 http://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/INDEX.bz2
> fetch -o INDEX-fr.bz2 http://ftp.fr.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/INDEX.bz2
> ls -l
total 2656
-rw-r--r--  1 marcin  users  1326192 Jul 27 05:36 INDEX-fr.bz2
-rw-r--r--  1 marcin  users  1352557 Jul 11 03:49 INDEX-xx.bz2

> bzgrep ^firefox-3.6 INDEX*.bz2 | cut -f1 -d\|
INDEX-fr.bz2:firefox-3.6.7,1
INDEX-xx.bz2:firefox-3.6.4,1

> fetch http://ftp.fr.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/All/firefox-3.6.7,1.tbz
fetch: http://ftp.fr.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/All/firefox-3.6.7,1.tbz: Not Found
> fetch http://ftp.fr.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/All/firefox-3.6.4,1.tbz
firefox-3.6.4,1.tbz                             0% of   18 MB  104 kBps^C

yet it does not have those packages.

How could something like this happen ?