Using rvm, and an empty gemset, I get this:
$ gem install chef --no-ri --no-rdoc
ERROR: While executing gem ... (Gem::DependencyError)
Unable to resolve dependencies: chef requires net-ssh (~> 2.2.2); net-ssh-multi requires net-ssh (>= 2.6.5); net-ssh-gateway requires net-ssh (>= 2.6.5)
I've tried resolving it by installing earlier versions of net-ssh-gateway and net-ssh-multi, but net-ssh-multi version 1.1 confounds me by installing 1.1.2.
Here's my first workaround to succeed:
gem install net-ssh -v 2.2.2 --no-ri --no-rdoc
gem install net-ssh-gateway -v 1.1.0 --no-ri --no-rdoc --ignore-dependencies
gem install net-ssh-multi -v 1.1.0 --no-ri --no-rdoc --ignore-dependencies
gem install chef --no-ri --no-rdoc