fix: Set default shell version values on POSIX entrypoint

[kurochan]

Summary

Add default values for BASH_VERSION, ZSH_VERSION, KSH_VERSION.

Shell which sets option nounset occurs following error.

$ /opt/homebrew/opt/asdf/libexec/asdf.sh:68: BASH_VERSION: parameter not set

[hyperupcall]

Nice catch!

To properly address this, the variables cannot be exported and should not be assigned to because this changes the shell environment.

So the :- variable substitutions have to be inline whenever each of those variables are used

[kurochan]

@hyperupcall
Thanks for the review. It was indeed causes breaking changes 😱
Fixed at ebe7310 .

[hyperupcall]

LGTM! Waiting for other maintainers to give feedback / take action

[hannestyden]

Happy to see that this fix is available already so I don't have to file it myself. 🙇:blush:

[kurochan]

But unfortunately, it has not yet been approved and released 😢

[hyperupcall]

I would merge this if I could - the maintainers seem to be merging things less frequently these days. For now, I have cherry-picked this commit (and others from other PRs) into fox-incubating/asdf, one of my forks.

All I can do is release a new version from my fork. I plan to add other features as well.

[jthegedus]

Thanks! And thanks for the review @hyperupcall 🙇‍♂️