Duplicating the options hash in Date#advance to prevent modification of the original [#1133 state:resolved]

Signed-off-by: Joshua Peek <josh@joshpeek.com>

activesupport/lib/active_support/core_ext/date/calculations.rb

@@ -92,6 +92,7 @@ module ActiveSupport #:nodoc:
         # Provides precise Date calculations for years, months, and days.  The +options+ parameter takes a hash with
         # any of these keys: <tt>:years</tt>, <tt>:months</tt>, <tt>:weeks</tt>, <tt>:days</tt>.
         def advance(options)
+          options = options.dup
           d = self
           d = d >> options.delete(:years) * 12 if options[:years]
           d = d >> options.delete(:months)     if options[:months]

activesupport/test/core_ext/date_ext_test.rb

@@ -250,6 +250,12 @@ class DateExtCalculationsTest < Test::Unit::TestCase
     Time.zone_default = nil
   end
 
+  def test_date_advance_should_not_change_passed_options_hash
+    options = { :years => 3, :months => 11, :days => 2 }
+    Date.new(2005,2,28).advance(options)
+    assert_equal({ :years => 3, :months => 11, :days => 2 }, options)
+  end
+
   protected
     def with_env_tz(new_tz = 'US/Eastern')
       old_tz, ENV['TZ'] = ENV['TZ'], new_tz