Enable new config option in generated spec_helper.rb.

lib/rspec/core/project_initializer/spec/spec_helper.rb

@@ -40,6 +40,13 @@
     mocks.verify_partial_doubles = true
   end
 
+  # This option will default to `:apply_to_host_groups` in RSpec 4 (and will
+  # have no way to turn it off -- the option exists only for backwards
+  # compatibility in RSpec 3). It causes shared context metadata to be
+  # inherited by the metadata hash of host groups and examples, rather than
+  # triggering implicit auto-inclusion in groups with matching metadata.
+  config.shared_context_metadata_behavior = :apply_to_host_groups
+
 # The settings below are suggested to provide a good initial experience
 # with RSpec, but feel free to customize to your heart's content.
 =begin