Puppet 3.X is now broken on Amazon AWS due to Ruby 2.0 being the default

Last week Amazon updated their AMIs (distributions) and repositories to 2014.03 and changed the default Ruby version from 1.8 to 2.0

e.g.:
– old behaviour
rubygems = rubygems-1.8.25-8.12.amzn1
– new behaviour
rubygems = rubygems-2.0-0.3.amzn1
– to get rubygems 1.8
rubygems18 = rubygems-1.8.25-8.12.amzn1

After these changes, Puppet crashes with the following error

/usr/share/ruby/vendor_ruby/2.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- puppet/util/command_line (LoadError)

	from /usr/share/ruby/vendor_ruby/2.0/rubygems/core_ext/kernel_require.rb:55:in `require'

	from /usr/bin/puppet:3:in `<main>'

I was able to replicate this same behaviour on new fresh instances with nothing else installed, using puppetlabs.repo, with both 3.2.3 stable and 3.5.0-RC3 devel.

Editing /usr/bin/puppet with these changes temporary fixes the problem

- #!/usr/bin/ruby

+ #!/usr/bin/ruby18

but Amazon will be removing in the near future ruby 1.8 and Puppet's documentation say 2.0 is supported