Bug#69482: multi-CD apt-get misbehaves when debs also available via ftp

[Malcolm Gillies <M.B.Gillies@pharm.uu.nl>]

Package: apt
Version: 0.3.19

'apt-get dist-upgrade' seems to lose the ability to find debs across
multiple CDs (configured with apt-cdrom) when the same files are also
available via ftp.

For instance, given the following /etc/apt/sources.list

    # CDs
    
    deb cdrom:[Debian GNU/Linux 2.2 r0 _Potato_ - Official i386 Binary-1 (20000814)]/ unstable contrib main non-US/contrib non-US/main
    deb cdrom:[Debian GNU/Linux 2.2 r0 _Potato_ - Official i386 Binary-2 (20000814)]/ unstable contrib main non-US/contrib non-US/main
    deb cdrom:[Debian GNU/Linux 2.2 r0 _Potato_ - Official i386 Binary-3 (20000814)]/ unstable contrib main non-US/contrib non-US/main
    
    # vital updates
    
    deb ftp://ftp.nl.uu.net/pub/linux/debian potato main contrib
    deb ftp://ftp.nl.uu.net/pub/linux/debian-non-US potato/non-US main contrib
    deb http://security.debian.org/debian-security potato/updates main contrib non-free
    
The following (slightly edited) transcript ensues:

     # apt-get --fix-broken --show-upgraded -o APT::Force-LoopBreak=1 dist-upgrade
    Reading Package Lists... Done
    Building Dependency Tree... Done
    Calculating Upgrade... Done
    The following packages will be REMOVED:
    [...]
    The following NEW packages will be installed:
    [...]
    The following packages have been kept back
    [...]
    The following packages will be upgraded
    [...]
    524 packages upgraded, 73 newly installed, 22 to remove and 27 not upgraded.
    Need to get 0B/234MB of archives. After unpacking 104MB will be used.
    Do you want to continue? [Y/n] y
    5% [Working]^MMedia Change: Please insert the disc labeled 'Debian GNU/Linux 2.2 r0 _Potato_ - Official i386 Binary-1 (20000814)' in the drive '/cdrom/' and press enter
    27% [Working]^MErr cdrom://[Debian GNU/Linux 2.2 r0 _Potato_ - Official i386 Binary-2 (20000814)] unstable/main ascd 0.13.1-2
      Wrong CD
    28% [Connecting to 193.67.79.170 (193.67.79.170)]^MErr ftp://193.67.79.170 potato/main ascd 0.13.1-2
      Cannot initiate the connection to 193.67.79.170 (193.67.79.170). - connect (101 Network is unreachable)
    
apt-get fails to ask for the Binary-2 CD and reverts to downloading the
files from ftp (which fails in this case because there is no PPP session up).

I noted this problem trying to upgrade from slink to potato, but the
problem has remained post-upgrade.

I'm running kernel 2.0.36 and libc-2.1.3

cheers,

Malcolm