Pkg: migrate versioned package directory after version update

[kmsquire]

After the update from v0.2 to v0.3, the few of us (?) who have versioned package directories suddenly can't see our packages (because we don't have a .julia/v0.3 directory).

When running an updated version of julia for the first time, it would be nice to have a way create and migrate packages from the previous version.

[StefanKarpinski]

cp -a ~/.julia/v0.{2,3}?

[kmsquire]

That's what I did by hand. But it might need to be more involved for someone updating from, e.g., v0.4 to v1.0.

[IainNZ]

👎 on this feature. @kmsquire, do you still want this?

[jakebolewski]

I don't think we want to support this feature.

[tkelman]

I think the time-saving way to do this is by copying ~/.julia/v0.3/REQUIRE to ~/.julia/v0.4/REQUIRE then doing a resolve or update.

[kmsquire]

Something like @tkelman's suggestion would be nice, although it should be opt-in--maybe some function in Pkg? Maybe Pkg.migrate() (with a flock of ascii birds on the screen as it does its thing)?