And rbenv doesn't nest. If your Ruby program execs another Ruby program, rbenv won't use the correct interpreter.

https://github.com/sstephenson/rbenv/issues/121

Who needs gemsets? Isn't that the point of Bundler?

Gemsets are still useful. see http://tenderlovemaking.com/2011/11/30/psa-the-number-of-gem...

Thank you for this, I did not realize it was the case but it definitely makes sense. Back to using gemsets I suppose...

I'd rather do gemsets than preface commands with "bundle exec"

yes! Though I just discovered the other day you can use the --binstubs option which obviates the need to use bundle exec in the project

Isn't that exchanging bundle exec command for ./bin/command ? Still not as convenient as just using command

Yeah, the plugin architecture is cool. There's one for bundler, too: https://github.com/carsomyr/rbenv-bundler