[bug][edge] rake fails with power_enum-2.7.0

[taro-k]

https://travis-ci.org/bborn/communityengine/jobs/163000989

$ ruby --version
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]
$ rvm --version
rvm 1.26.10 (latest-minor) by Wayne E. Seguin wayneeseguin@gmail.com, Michal Papis mpapis@gmail.com [https://rvm.io/]
$ bundle --version
Bundler version 1.7.9
$ gem --version
2.4.5
install.bundler
$ bundle install --binstubs --path=${BUNDLE_PATH:-vendor/bundle}
$ bundle exec rake db:drop db:create db:migrate test
/home/travis/build/bborn/communityengine/test/testapp/Rakefile
DEPRECATION WARNING: [paperclip] [deprecation] AWS SDK v1 has been deprecated in paperclip 5. Please consider upgrading to AWS 2 before upgrading paperclip. (called from class:HomepageFeature at /home/travis/build/bborn/communityengine/app/models/homepage_feature.rb:2)
rake aborted!

I already confirmed this error disappears with Ruby-2.2.5:
https://travis-ci.org/taro-k/communityengine/builds/163019279
but it should be fixed now.

[taro-k]

The above log continues as follows:

ArgumentError: wrong number of arguments (5 for 4)
/home/travis/build/taro-k/communityengine/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.7.1/lib/active_record/reflection.rb:218:in initialize' /home/travis/build/taro-k/communityengine/vendor/bundle/ruby/2.2.0/gems/power_enum-2.7.0/lib/power_enum/reflection.rb:50:ininitialize'

I reproduced this error in my local:

% ruby -v
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]
% rbenv -v
rbenv 1.0.0-31-gd0779fc
% bundle -v
Bundler version 1.7.9
% gem --version
2.4.5

In this care, power_enum-2.7.0 is installed.
As compared to other results in Travis, at least the combination of ruby 2.2.0p0 and bundle-1.7.* install power_enum-2.7.0, otherwise, power_enum-2.9.1 is installed.
The power_enum-2.7.0 (and 2.7.1) causes the error.
Also, there seems a bug of ~>, Pessimistic operator or Twiddle-wakka:
https://robots.thoughtbot.com/rubys-pessimistic-operator