XML values can be nil

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6582 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/lib/active_support/core_ext/hash/conversions.rb

@@ -173,7 +173,7 @@ def typecast_xml_value(value)
                     
                     # Turn { :files => { :file => #<StringIO> } into { :files => #<StringIO> } so it is compatible with
                     # how multipart uploaded files from HTML appear
-                    if xml_value["file"].is_a?(StringIO)
+                    if xml_value && xml_value["file"].is_a?(StringIO)
                       xml_value["file"]
                     else
                       xml_value