[issue204] do not remove packages when auto-upgrading

[Antoine Pitrou at Labix Tracker]

Antoine Pitrou <pitrou at free.fr> added the comment:

Hmm, ok, got into the code.
I first tried to create a PolicyUpgradeWithoutRemove, but it's not sufficient.
One has to modify Translation._install in the part that "removes packages with
the same name that can't coexist with this one", so to distinguish between
really locked packages (locked in a given version) and "soft-locked" (locked
only by name).

Current interaction between Translation and Policy objects is not fine-grained
enough. Can I add a field in Policy to support desired behaviour by listing
soft-locked packages (protected by name)?

By the way, the RPM format has a notion of "obsoletes" packages which may be
relevant here. But, AFAIU by reading the code, the obsoletes info is simply
added to the conflict info, while there may be some semantic difference:
removing an obsolete package shouldn't do harm while removing a conflicting
package probably does. 

What do you think? Am I totally off base?

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status: unread -> chatting

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