Fixed problem where `1.day.eql?(1.day)` is false

This fixes:
    1.second.eql?(1.second) #=> false

The new `eql?` requires that `other` is an `ActiveSupport::Duration`.
This requirement makes `ActiveSupport::Duration`'s behavior consistent
with other numeric types in Ruby.

    1.eql?(1.0) #=> false
    1.0.eql?(1) #=> false

    1.second.eql?(1) #=> false (was true)
    1.eql?(1.second) #=> false

    { 1 => "foo", 1.0 => "bar" }
    #=> { 1 => "foo", 1.0 => "bar" }

    { 1 => "foo", 1.second => "bar" }
    # now => { 1 => "foo", 1.second => "bar" }
    # was => { 1 => "bar" }

And though the behavior here hasn't changed, for reference:

    1 == 1.0 #=> true
    1.0 == 1 #=> true

    1 == 1.second #=> true
    1.second == 1 #=> true

1 files changed, 7 insertions, 0 deletions

diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index 28ba33331e..c8f17f4618 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -31,6 +31,13 @@ class DurationTest < ActiveSupport::TestCase
     assert !(1.day == 'foo')
   end
 
+  def test_eql
+    assert 1.minute.eql?(1.minute)
+    assert 2.days.eql?(48.hours)
+    assert !1.second.eql?(1)
+    assert !1.eql?(1.second)
+  end
+
   def test_inspect
     assert_equal '0 seconds',                       0.seconds.inspect
     assert_equal '1 month',                         1.month.inspect