Fix handling of negative zero in number_to_currency

Author: jaredbeck

activesupport/lib/active_support/number_helper.rb

@@ -111,7 +111,7 @@ def number_to_currency(number, options = {})
       unit      = options.delete(:unit)
       format    = options.delete(:format)
 
-      if number.to_f < 0
+      if number.to_f.phase != 0
         format = options.delete(:negative_format)
         number = number.respond_to?("abs") ? number.abs : number.sub(/^-/, '')
       end

activesupport/test/number_helper_test.rb

@@ -64,6 +64,8 @@ def test_number_to_currency
           assert_equal("$1,234,567,890.50", number_helper.number_to_currency("1234567890.50"))
           assert_equal("1,234,567,890.50 Kč", number_helper.number_to_currency("1234567890.50", {:unit => "Kč", :format => "%n %u"}))
           assert_equal("1,234,567,890.50 - Kč", number_helper.number_to_currency("-1234567890.50", {:unit => "Kč", :format => "%n %u", :negative_format => "%n - %u"}))
+          assert_equal("0.00", number_helper.number_to_currency(+0.0, {:unit => "", :negative_format => "(%n)"}))
+          assert_equal("(0.00)", number_helper.number_to_currency(-0.0, {:unit => "", :negative_format => "(%n)"}))
         end
       end