chicken-install uninstalls eggs on updating

[Mario Domenech Goulart]

When we install an egg X that depends on a certain version of egg Y, and we have a version of egg Y installed, but not the minimum version required by X, chicken-installs prompts for an update. If we decide to update Y to the version required by X, chicken-install first uninstalls Y.

This is dangerous. If for any reason Y or any egg in the dependencies chain of Y fail (it has to be reinstalled, after all), we end up in a situation worse than we were before installing X, since, besides not installing X, Y was removed.

Here's a practical example:

checking dependencies for `awful-static-pages' ...

The following installed extensions are outdated, because `awful-static-pages' requires later versions:
  awful (0.39.2 -> 0.40.0)

Do you want to replace the existing extensions? (yes/no/abort) yes
 upgrade: awful
removing previously installed extension `awful' ...
  rm -fr '/home/mario/local/chicken-4.8.2/lib/chicken/7/awful.so'
  rm -fr '/home/mario/local/chicken-4.8.2/lib/chicken/7/awful.import.so'
  rm -fr '/home/mario/local/chicken-4.8.2/lib/chicken/7/awful.setup-info'

...

What if the installation of the new awful fails?

This situation can be potentially more dangerous if the CHICKEN installation is old. Testing new egg versions against old CHICKEN versions is not usual, so they are much more prone to breakage.

[sjamaan]

Seems to me this should be done as part of the overhaul of the installation system, or afterwards.

[sjamaan]

Would probably be reasonably tricky and lots of work, but not necessarily hard

[sjamaan]

The new chicken-install doesn't uninstall when upgrading anymore.