cannot create test application in spec

[vkdimitrov]

I cannot create test app following contributions guidelines, so my pull requests fail on Travis checks branch: 3-1-stable

spree_social$ bundle exec rake test_app
Expected string default value for '--rc'; got false (boolean)
rake aborted!
NoMethodError: undefined method `last_comment' for #<Rake::Application:0x00000003677480>
/home/vkdimitrov/.rvm/gems/ruby-2.2.3/gems/rspec-core-3.2.3/lib/rspec/core/rake_task.rb:84:in `define'
/home/vkdimitrov/.rvm/gems/ruby-2.2.3/gems/rspec-core-3.2.3/lib/rspec/core/rake_task.rb:60:in `initialize'
/home/vkdimitrov/work/spree_social/Rakefile:7:in `new'
/home/vkdimitrov/work/spree_social/Rakefile:7:in `<top (required)>'
/home/vkdimitrov/.rvm/gems/ruby-2.2.3/gems/rake-12.0.0/exe/rake:27:in `<top (required)>'
/home/vkdimitrov/.rvm/gems/ruby-2.2.3/bin/ruby_executable_hooks:15:in `eval'
/home/vkdimitrov/.rvm/gems/ruby-2.2.3/bin/ruby_executable_hooks:15:in `<main>'
(See full trace by running task with --trace)