What mirrors serve upgraded package version? (firefox-esr 52.2.0esr-1~deb8u1)

[Alessandro Vesely <vesely@tana.it>]

Hi all!

https://packages.debian.org/jessie/firefox-esr says version 52.2.0esr-1~deb8u1

However, after running apt-get update, I get

root@pcale:~# apt-cache policy firefox-esr
firefox-esr:
  Installed: 45.9.0esr-1~deb8u1
  Candidate: 45.9.0esr-1~deb8u1
  Version table:
 *** 45.9.0esr-1~deb8u1 0
        500 http://debian.fastweb.it/debian/ jessie/main amd64 Packages
        500 http://ftp.it.debian.org/debian/ jessie/main amd64 Packages
        500 http://mirror.iway.ch/debian/ jessie/main amd64 Packages
        100 /var/lib/dpkg/status

In fact, that's what I have installed (`firefox --version` is Mozilla Firefox 45.9.0)

Debian Security Advisory DSA-3881-1 by Moritz Muehlenhoff came on June 14, 2017.
It says:
    For the stable distribution (jessie), these problems have been fixed in
    version 52.2.0esr-1~deb8u1.

I don't think the three mirrors I configured are still behind.  What's wrong?

BTW, is there a script to check what versions of a given package exist where?

Thanks
Ale