alt Hacker NewsPresumably the ones where you are expected to have the latest version of everything and make a new package if you break that (python2 → python3)
Not sure why more ecosystems don't do this. Sure an update could break dependents, but, like, you already have a big problem if a dependent was keeping you on an old version no matter what.
Building a SAT solver into the package manager seems to be a solution in search of a problem.
> Building a SAT solver into the package manager seems to be a solution in search of a problem.
I can't tell you which ones off the top of my head, but I'm sure a number of package managers do use constraint solvers to find dependencies matching the constraints.