official mirrors failing to update some packages

[Alex Muntada]

Has anyone running an official mirror seen problems updating package
lists recently?

$ sudo do-release-upgrade
...
Error during update

A problem occurred during the update. This is usually some sort of
network problem, please check your network connection and retry.

W:Failed to fetch
gzip:/var/lib/apt/lists/partial/ftp.caliu.cat_pub_distribucions_ubuntu_archive_dists_trusty_main_binary-amd64_Packages
Hash Sum mismatch
, W:Failed to fetch
gzip:/var/lib/apt/lists/partial/ftp.caliu.cat_pub_distribucions_ubuntu_archive_dists_trusty_universe_binary-i386_Packages
Hash Sum mismatch
, E:Some index files failed to download. They have been ignored, or
old ones used instead.


This is the summary of my research about this today:

* changed the way we updated our mirror from our own rsync recipe to
the ubumirror package (no change);
* used https://github.com/marblenix/fix-apt-mirror-hash-sum-mismatch
to make sure that the files in our mirror were up to date (no change);
* downloaded the offending files with wget from both
archive.ubuntu.com and ftp.caliu.cat, compared them and were exactly
the same;
* search our nginx log files for errors: the only surprise was that
offending files are downloaded as partial content (http 206) and
sometimes ranges fail (with http 416);
* figured out that the only difference between country level archives
and our own is that ours uses nginx and the others apache;

I'm not sure yet, but i'm afraid that there's been some change in the
way apt manages files (trying to fetch partial content in some cases)
and some servers fail to work correctly making apt complain about the
network. Does this makes any sense?

https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1311652/comments/4

Thanks,
Alex