emerge -p =dev-ruby/minitest-1.5.0

These are the packages that would be merged, in order:

Calculating dependencies... done!


[nomerge      ] dev-ruby/minitest-1.5.0  USE="test -doc" RUBY_TARGETS="ruby18 -jruby" 
[nomerge      ]  dev-ruby/hoe-2.6.1  USE="test -doc" RUBY_TARGETS="ruby18 -jruby -ree18 (-ruby19)" 
[ebuild  N    ]   virtual/ruby-minitest-0-r1  RUBY_TARGETS="ruby18 -jruby -ree18 (-ruby19)" 0 kB
[ebuild  N    ]   dev-ruby/rubyforge-2.0.4-r1  USE="test -doc" RUBY_TARGETS="ruby18 -jruby -ree18 (-ruby19)" 15 kB
[ebuild  N    ] dev-ruby/minitest-1.5.0  USE="test -doc" RUBY_TARGETS="ruby18 -jruby" 22 kB
[ebuild  N    ]  dev-ruby/hoe-2.6.1  USE="test -doc" RUBY_TARGETS="ruby18 -jruby -ree18 (-ruby19)" 113 kB

Total: 4 packages (4 new), Size of downloads: 149 kB

 * Error: circular dependencies:

('ebuild', '/', 'dev-ruby/hoe-2.6.1', 'merge') depends on
  ('ebuild', '/', 'virtual/ruby-minitest-0-r1', 'merge') (buildtime)
  ('ebuild', '/', 'dev-ruby/rubyforge-2.0.4-r1', 'merge') (buildtime)
('ebuild', '/', 'dev-ruby/minitest-1.5.0', 'merge') depends on
  ('ebuild', '/', 'dev-ruby/hoe-2.6.1', 'merge') (buildtime)
('ebuild', '/', 'dev-ruby/rubyforge-2.0.4-r1', 'merge') depends on
  ('ebuild', '/', 'dev-ruby/hoe-2.6.1', 'merge') (buildtime)
('ebuild', '/', 'virtual/ruby-minitest-0-r1', 'merge') depends on
  ('ebuild', '/', 'dev-ruby/minitest-1.5.0', 'merge') (runtime)

 * Note that circular dependencies can often be avoided by temporarily
 * disabling USE flags that trigger optional dependencies.