Replace Gregorian/Julian chrono with ISO in date.rb

patch.diff

diff --git a/lib/ruby/stdlib/date.rb b/lib/ruby/stdlib/date.rb
index ad36703759..d40bf7073a 100644
--- a/lib/ruby/stdlib/date.rb
+++ b/lib/ruby/stdlib/date.rb
@@ -712,7 +712,7 @@ class Date
       end
 
       chrono = if sg == ITALY
-        JODA.chrono::GJChronology
+        JODA.chrono::ISOChronology
       elsif sg == JULIAN
         JODA.chrono::JulianChronology
       elsif sg == GREGORIAN
@@ -724,7 +724,7 @@ class Date
       else
         constructor = JODA::Instant.java_class.constructor(Java::long)
         cutover = constructor.new_instance JODA::DateTimeUtils.fromJulianDay(jd_to_ajd(sg, 0))
-        JODA.chrono::GJChronology.getInstance(tz, cutover)
+        JODA.chrono::ISOChronology.getInstance(tz, cutover)
       end
     end
   end
@@ -735,7 +735,7 @@ class Date
   DEFAULT_TZ = ENV['TZ']
   DEFAULT_DTZ = JODA::DateTimeZone.getDefault
   CHRONO_ITALY_DEFAULT_DTZ = chronology(ITALY, DEFAULT_DTZ)
-  CHRONO_ITALY_UTC = JODA.chrono::GJChronology.getInstance(JODA::DateTimeZone::UTC)
+  CHRONO_ITALY_UTC = JODA.chrono::ISOChronology.getInstance(JODA::DateTimeZone::UTC)
 
   # Is a year a leap year in the Julian calendar?
   #