v0.3.0 "Fixed" the package name for bundler to 'bundler' on all Debian-like systems. This is incorrect, as Ubuntu uses 'ruby-bundler' on at least 12.04.
The package name was correct in v0.2.1. The changelog entry reads:
- Fix package name to be 'bundler' instead of 'ruby-bundler' for Debian/Ubuntu
This may have been an incorrect fix for #1224, relating to the package name specifically on Debian Wheezy, and possible new versions of Ubuntu.
Relevant class is Ruby::Params ($bundler_package).