Test Failures with ruby 2.5.1

[Crisfole]

To reproduce:

if rbenv versions | grep 2.5.1 -q; then
  echo '2.5.1 already installed'
else
  rbenv install 2.5.1
fi
rbenv local 2.5.1
bin/setup
bundle exec appraisal rake test

You'll get a SystemStackError because of the ::Bignum ::Fixnum merge. I don't fully understand the issue because I stopped reading the explanation, but it has to do with rails < 5.0 and ruby >= 2.4.0 and how rails sniffs integer types (https://stackoverflow.com/a/41504382/456188).

[wkirby]

Gross.