Fix not respecting the parent's #enable_processing value after readin…

…g its own

Fixes #2676

lib/carrierwave/uploader/versions.rb

@@ -27,6 +27,17 @@ def build(superclass)
           @klass.processors = []
           @klass.version_options = @options
           @klass.class_eval <<-RUBY, __FILE__, __LINE__ + 1
+            # Define the enable_processing method for versions so they get the
+            # value from the parent class unless explicitly overwritten
+            def self.enable_processing(value=nil)
+              self.enable_processing = value if value
+              if defined?(@enable_processing) && !@enable_processing.nil?
+                @enable_processing
+              else
+                superclass.enable_processing
+              end
+            end
+
             # Regardless of what is set in the parent uploader, do not enforce the
             # move_to_cache config option on versions because it moves the original
             # file to the version's target file.

spec/uploader/versions_spec.rb

@@ -111,6 +111,13 @@ def store_dir
       expect(@uploader.thumb.enable_processing).to be_truthy
     end
 
+    it "should use the enable processing value of the parent after reading its own value" do
+      @uploader_class.version :thumb
+      @uploader.cache!(File.open(file_path('test.jpg')))
+      @uploader_class.enable_processing = false
+      expect(@uploader.thumb.class.enable_processing).to be_falsey
+    end
+
     it "should reopen the same class when called multiple times" do
       @uploader_class.version :thumb do
         def self.monkey