Merge branch 'ruby-2.2'

* ruby-2.2:
  Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314

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

@@ -151,7 +151,11 @@ def utc_offset
   # Layers additional behavior on DateTime#<=> so that Time and
   # ActiveSupport::TimeWithZone instances can be compared with a DateTime.
   def <=>(other)
-    super other.to_datetime
+    if other.respond_to? :to_datetime
+      super other.to_datetime
+    else
+      nil
+    end
   end
 
 end

activesupport/lib/active_support/values/time_zone.rb

@@ -234,6 +234,7 @@ def formatted_offset(colon=true, alternate_utc_string = nil)
     # Compare this time zone to the parameter. The two are compared first on
     # their offsets, and then by name.
     def <=>(zone)
+      return unless zone.respond_to? :utc_offset
       result = (utc_offset <=> zone.utc_offset)
       result = (name <=> zone.name) if result == 0
       result