chruby uses the same GEM_HOME for multiple TruffleRuby releases

[eregon]

Which means it might reuse C extensions compiled on a different TruffleRuby version, which is very likely to not work.

Related to #1715 and postmodern/chruby#410.

Other Ruby managers seem not affected:

• RVM uses a different GEM_HOME for each installed Ruby.
• rbenv does not set the GEM_* environment variables AFAIK, and so installs gem under the Ruby's prefix.

[eregon]

Fixed in chruby in postmodern/chruby#419 but there is not yet a release a chruby containing the fix (cc @postmodern).

[eregon]

I close this because it is clearly chruby bug, nothing to change in truffleruby.