Doesn't allow upgrade to natty due to 'ubuntu-minimal missing' when it is present

[Wookey]

Binary package hint: update-manager

run update-manager, select 'upgrade' (to natty), when offered.
warning that some 3rd-party sources are being adjusted, then dialog:
"After your package information was updated the essential package 'ubuntu-minimal' can not be found anymore. This indicates a serious error, please report this bug...."

So I am.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: update-manager 1:0.142.23
ProcVersionSignature: Ubuntu 2.6.35-28.50-generic 2.6.35.11
Uname: Linux 2.6.35-28-generic x86_64
Architecture: amd64
Date: Tue May 17 16:56:34 2011
PackageArchitecture: all
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_GB.utf8
SourcePackage: update-manager

[Wookey (wookey)]

Ubuntu-minimal is installed:
wookey@e102475-lin:~$ apt-cache policy ubuntu-minimal
ubuntu-minimal:
  Installed: 1.207
  Candidate: 1.207
  Version table:
     1.207+aarch64v1 0
        500 copy:/srv/repos/ maverick-aarch64/main amd64 Packages
 *** 1.207 0
        990 http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick/main amd64 Packages
        100 /var/lib/dpkg/status

So I'm not sure why update-manager can't find it.

here is my /etc/apt/sources.list

### This source file has been modified to point to ARMs internal mirror which houses most repositories.
### We currently not keep the multiverse repositories locally based on the definition of the contents
### outlined by Ubuntu/Canonical. The Sources are still available and are left unmodified below where needed.
### Please read the guidance on the difference between the different package types provided by canonical
### here:- http://www.ubuntu.com/project/about-ubuntu/components

### Wiki location for ARMs mirror setup:- http://wiki.emea.arm.com/Sysadmin/UbuntuMirrorUser

deb http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick main restricted universe
deb-src http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick main restricted universe

#deb http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ natty main restricted universe
#deb-src http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ natty main restricted universe

deb http://e102475-lin/obanrepo natty-aarch64 main

## Major bug fix updates produced after the final release of the distribution.
deb http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick-updates main restricted universe
deb-src http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick-updates main restricted universe

deb http://gb.archive.ubuntu.com/ubuntu/ maverick multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ maverick multiverse
deb http://gb.archive.ubuntu.com/ubuntu/ maverick-updates multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ maverick-updates multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
#deb http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ karmic-backports main restricted universe
# deb-src http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ karmic-backports main restricted universe
#deb http://gb.archive.ubuntu.com/ubuntu/ karmic-backports multiverse
# deb-src http://gb.archive.ubuntu.com/ubuntu/ karmic-backports multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu karmic partner
# deb-src http://archive.canonical.com/ubuntu karmic partner

#deb http://arm-security-ubuntu.cambridge.arm.com/ubuntu/ karmi...

[Wookey (wookey)]

OK, the problem here is that my main archive is the internal arm one:
deb http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick main restricted universe
deb-src http://arm-archive-ubuntu.cambridge.arm.com/ubuntu/ maverick main restricted universe

So once the installer has sanitized your repo set to remove 3rd-party ones there is nothing left so it goes 'help, it's all broken!'.

It would be nice if it gave a more helpful error message at least like 'you have no main repositories left after I sanitised things' rather than trying to tell you a package you _do_ have is not present. Even better would be to be a bit more liberal/smart and say 'is this a mirror of the ubuntu archive?'

[Wookey (wookey)]

This bug still exists in natty-> oneiric transition. Having a local archive means you can't upgrade with update-manager and you get a very mysterious message about it. This is update-manager: 1:0.150.5