Ruby gc not collecting array

gc_test.rb

THE_STRING = 'a random 369-characterish string'

def self.find_array
  ObjectSpace.each_object Array do |array|
    return array if array.any? && array.all? { |s| s == THE_STRING }
  end
  nil
end

def self.print_whether_array_exists
  if array = find_array
    puts "IT EXISTS WITH SIZE #{array.size}"
  else
    puts "IT DOES NOT EXIST"
  end
end

array = []
require 'time'
time = Time.now + 2
array << THE_STRING while time > Time.now

print_whether_array_exists
array = nil
GC.enable
GC.start
print_whether_array_exists

Looks like a bug in MRI to me:

$ ruby -v gc.rb
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]
IT EXISTS WITH SIZE 2716941
IT EXISTS WITH SIZE 2716941

Rubinius GC's it as expected:

$ ruby -v gc.rb
rubinius 3.48 (2.3.1 b39b6dda 2016-07-20 3.6.2) [x86_64-darwin15.5.0]
IT EXISTS WITH SIZE 2042403
IT DOES NOT EXIST