Be better about upgrading old versions of packages

[tkelman]

ref JuliaLang/IJulia.jl#329 (comment)

We may want to only do this if we detect a Julia version upgrade - breaking an existing setup due to upstream changes from opensuse might not be pleasant for users.

[stevengj]

In the meantime, I'd like to add a workaround to the IJulia troubleshooting README. Is the right workaround to do rm(Pkg.dir("WinRPM","deps","usr"), recursive=true) followed by Pkg.build("IJulia")?

[tkelman]

Removing is a bit drastic and leaves people without a way to get back to what they had before, so I'd rather recommend moving it to a backup name as a first step. Especially since the opensuse downloads are flaky for some people (#44), and fully upgrading all WinRPM packages could lead to a previously working setup breaking for some older releases of Julia.

[tkelman]

Testing this now, and it looks like you'll also likely need to move Pkg.dir("WinRPM", "installed.list") out of the way as well, to force all packages to re-download.

[vtjnash]

WinRPM.update() only updates the metadata, so it isn't really the right function for this.

For this, there needs to be a WinRPM.upgrade function added that parses installed.list and calls Pkg.install on the list of all currently installed packages.

[stevengj]

Yes please!

[davidanthoff]

And another vote here, I just came across that for https://github.com/WizardMac/ReadStat.jl. The C library that ReadStat.jl wraps is probably going to be updated from time to time, and if I understand this issue here correctly, users won't get those updated DLLs automatically once they have downloaded an old version, right? That would probably be a pretty serious issue for that package.

[tkelman]

you could add a validation hook to check that the binaries are acceptable. not sure whether that would force a redownload.