On a clean system:

$ gem install arvados arvados-cli
Fetching: arvados-1.1.4.20180412190507.gem (100%)
Successfully installed arvados-1.1.4.20180412190507
Parsing documentation for arvados-1.1.4.20180412190507
Installing ri documentation for arvados-1.1.4.20180412190507
Done installing documentation for arvados after 0 seconds
Fetching: arvados-0.1.20180302192246.gem (100%)
Successfully installed arvados-0.1.20180302192246
Fetching: arvados-cli-1.1.4.20180723133344.gem (100%)
Successfully installed arvados-cli-1.1.4.20180723133344
Parsing documentation for arvados-0.1.20180302192246
Installing ri documentation for arvados-0.1.20180302192246
Parsing documentation for arvados-cli-1.1.4.20180723133344
Installing ri documentation for arvados-cli-1.1.4.20180723133344
Done installing documentation for arvados, arvados-cli after 0 seconds
3 gems installed

$ gem list |grep arv
arvados (1.1.4.20180412190507, 0.1.20180302192246)
arvados-cli (1.1.4.20180723133344)

Uninstalling the old one breaks things:

$ gem uninstall arvados -v=0.1.20180302192246

You have requested to uninstall the gem:
    arvados-0.1.20180302192246

arvados-cli-1.1.4.20180723133344 depends on arvados (>= 0.1.20150128223554, ~> 0.1)
If you remove this gem, these dependencies will not be met.
Continue with Uninstall? [yN]  y
Successfully uninstalled arvados-0.1.20180302192246

$ gem list |grep arv
arvados (1.1.4.20180412190507)
arvados-cli (1.1.4.20180723133344)

$ arv user current
/home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems/dependency.rb:310:in `to_specs': Could not find 'arvados' (>= 0.1.20150128223554, ~> 0.1) - did find: [arvados-1.1.4.20180412190507] (Gem::MissingSpecVersionError)
Checked in 'GEM_PATH=/home/ward/.rvm/gems/ruby-2.3.6:/home/ward/.rvm/gems/ruby-2.3.6@global', execute `gem env` for more information
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:1441:in `block in activate_dependencies'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:1430:in `each'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:1430:in `activate_dependencies'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems/specification.rb:1412:in `activate'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems.rb:300:in `block in activate_bin_path'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems.rb:300:in `synchronize'
    from /home/ward/.rvm/rubies/ruby-2.3.6/lib/ruby/site_ruby/2.3.0/rubygems.rb:300:in `activate_bin_path'
    from /home/ward/.rvm/gems/ruby-2.3.6/bin/arv:23:in `<main>'
    from /home/ward/.rvm/gems/ruby-2.3.6/bin/ruby_executable_hooks:15:in `eval'
    from /home/ward/.rvm/gems/ruby-2.3.6/bin/ruby_executable_hooks:15:in `<main>'