Downgrading packages after removing a repository

[Andrew Sayers]

You make a good point about breakage when packages are downgraded.  But 
it seems a little disingenuous for us to bend over backwards to make 
unsupported upgrades possible (adding a "software sources" menu item, 
putting PPAs in Launchpad, creating /etc/apt/sources.list.d/ and so on), 
then for us to walk away when those upgrades make systems unusable.

I also take your point that pain is an important way of communicating 
danger to users.  But making a system unusable seems like pushing a man 
off a cliff to warn him about the dangers of falling.

I would expect the message to be at least as effective if we had a GUI 
to say "warning: may cause breakage" on upgrade, "warning: breakage 
caused" on downgrade, and breakage evident from the loss of 
configuration data.  If that's acceptable to you, and if C's blueprint 
idea seems okay, then I'll include the GUI suggestions in the blueprint.

	- Andrew