Upgrade from 10.04 to 12.04 breaks if skype is installed

This happened to me today. I had to remove skype and a lot of i386 dependencies, also force installation of some packages with dpkg so I could finish the upgrade per se unblocking apt, and do an apt-get upgrade and apt-get dist-upgrade to fix the breakage.

Status changed to 'Confirmed' because the bug affects multiple users.

It's worth noting that my upgrade was from 11.10 to 12.04, not from 10.04 to 12.04.

Working this specifically as a 10.04->12.04 LTS issue, since that's what we have the logs for and since 11.10->12.04 is likely to be a different issue entirely.

The log shows the partner version of skype:amd64 installed, which is fine. In precise there's an updated version of this package which depends on skype-bin:i386.
 - we can't upgrade skype:amd64 because multiarch isn't enabled yet (it can't be until after the upgrade, since lucid's dpkg doesn't understand it).
 - keeping the lucid skype requires ia32-libs to be kept as a dependency.
  - we can't install the new ia32-libs because it *also* requires multiarch.
  - apt tries to keep the old version of ia32-libs, which requires lib32v4l-0 as a dependency (a biarch lib that exists for exactly this purpose).
   - lib32v4l-0 is only in lucid, since it's obsoleted by multiarch, and has a strict versioned dependency on the matching version of libv4l-0.
   - apt has already decided to upgrade libv4l-0, and refuses to hold it back in support of the above dep chain.

This seems like something that should be fixable with an update-manager hint about making libv4l-0 upgrades a lower priority, since lib4vl-0's shlibs point to a version much older than that in lucid. Holding back the chain, and allowing this handful of packages to be upgraded separately after the release upgrade, should solve this without having to remove skype.

Alternatively, we could just remove skype from update-manager's blacklist.

Michael, do you think it would be reasonable to drop skype from update-manager's blacklist? You added it back in 2009, there's no bug reference for it so I'm not sure what issue it was added to solve.

This was fixed in the upload of update-manager 1:0.156.12:

update-manager (1:0.156.12) precise; urgency=low
[...]
  [ Michael Vogt ]
[...]
  * remove skype from the removal blacklist

update-manager will now be able to complete the upgrade, even if skype must be removed in the process. The skype package can be reinstalled immediately after upgrade.