Release-upgrades should always use a local mirror

[Jerry Chong]

Binary package hint: update-manager

When attempting to update to the Maverick 10.10 beta, using "update-manager -c -d":

1. The DistUpgrade tool and its related Python packages, if I'm not wrong, was downloaded from the main US mirror "archive.ubuntu.com".
2. At the "Setting software channels" step after disabling 3rd party sources, the download mirror that is added to /etc/apt/sources.list is again the US mirror "http://archive.ubuntu.com/ubuntu". The original line in sources.list: "deb ftp://mirror.upm.edu.my/ubuntu/ lucid main universe multiverse restricted" is ignored and commented out instead.

So the main problem is that the Ubuntu upgrade is now subject to network conditions between the user's ISP and trunk line to the US (in my case, I suspect our ISPs have been throttling downloads from the US, so my download speed is incredibly slow compared to my ADSL plan's usual speed.) - even though it would have been trivially straightforward to determine which mirror the user has already chosen to use, and whether the mirror has up-to-date packages to support the Maverick upgrade.

Edit: Doh! Could no longer reproduce this behaviour, might have been a fluke.