Reverted the nil assignment, as the issue in Rails/Rack was fixed. Also removed a lot of logging.

lib/paperclip.rb

@@ -43,7 +43,7 @@ end
 # documentation for Paperclip::ClassMethods for more useful information.
 module Paperclip
 
-  VERSION = "2.2.7"
+  VERSION = "2.2.8"
 
   class << self
     # Provides configurability to Paperclip. There are a number of options available, such as:

lib/paperclip/attachment.rb

@@ -49,8 +49,6 @@ module Paperclip
 
       normalize_style_definition
       initialize_storage
-
-      log("Paperclip attachment #{name} on #{instance.class} initialized.")
     end
 
     # What gets called when you call instance.attachment = File. It clears
@@ -62,9 +60,6 @@ module Paperclip
     # If the file that is assigned is not valid, the processing (i.e.
     # thumbnailing, etc) will NOT be run.
     def assign uploaded_file
-      # This is because of changes in Rails 2.3 that cause blank fields to send nil
-      return nil if uploaded_file.nil?
-
       %w(file_name).each do |field|
         unless @instance.class.column_names.include?("#{name}_#{field}")
           raise PaperclipError.new("#{@instance.class} model does not have required column '#{name}_#{field}'")
@@ -77,16 +72,12 @@ module Paperclip
       end
 
       return nil unless valid_assignment?(uploaded_file)
-      log("Assigning #{uploaded_file.inspect} to #{name}")
 
       uploaded_file.binmode if uploaded_file.respond_to? :binmode
-      queue_existing_for_delete
-      @errors            = {}
-      @validation_errors = nil
+      self.clear
 
       return nil if uploaded_file.nil?
 
-      log("Writing attributes for #{name}")
       @queued_for_write[:original]   = uploaded_file.to_tempfile
       instance_write(:file_name,       uploaded_file.original_filename.strip.gsub(/[^\w\d\.\-]+/, '_'))
       instance_write(:content_type,    uploaded_file.content_type.to_s.strip)
@@ -149,13 +140,11 @@ module Paperclip
     # the instance's errors and returns false, cancelling the save.
     def save
       if valid?
-        log("Saving files for #{name}")
         flush_deletes
         flush_writes
         @dirty = false
         true
       else
-        log("Errors on #{name}. Not saving.")
         flush_errors
         false
       end
@@ -293,7 +282,7 @@ module Paperclip
     end
 
     def valid_assignment? file #:nodoc:
-      file.respond_to?(:original_filename) && file.respond_to?(:content_type)
+      file.nil? || (file.respond_to?(:original_filename) && file.respond_to?(:content_type))
     end
 
     def validate #:nodoc:
@@ -370,12 +359,10 @@ module Paperclip
     end
 
     def post_process_styles
-      log("Post-processing #{name}")
       @styles.each do |name, args|
         begin
           raise RuntimeError.new("Style #{name} has no processors defined.") if args[:processors].blank?
           @queued_for_write[name] = args[:processors].inject(@queued_for_write[:original]) do |file, processor|
-            log("Processing #{name} #{file} in the #{processor} processor.")
             Paperclip.processor(processor).make(file, args, self)
           end
         rescue PaperclipError => e
@@ -397,7 +384,6 @@ module Paperclip
 
     def queue_existing_for_delete #:nodoc:
       return unless file?
-      log("Queueing the existing files for #{name} for deletion.")
       @queued_for_delete += [:original, *@styles.keys].uniq.map do |style|
         path(style) if exists?(style)
       end.compact

lib/paperclip/storage.rb

@@ -36,11 +36,10 @@ module Paperclip
       alias_method :to_io, :to_file
 
       def flush_writes #:nodoc:
-        logger.info("[paperclip] Writing files for #{name}")
         @queued_for_write.each do |style, file|
           file.close
           FileUtils.mkdir_p(File.dirname(path(style)))
-          logger.info("[paperclip] -> #{path(style)}")
+          logger.info("[paperclip] saving #{path(style)}")
           FileUtils.mv(file.path, path(style))
           FileUtils.chmod(0644, path(style))
         end
@@ -48,10 +47,9 @@ module Paperclip
       end
 
       def flush_deletes #:nodoc:
-        logger.info("[paperclip] Deleting files for #{name}")
         @queued_for_delete.each do |path|
           begin
-            logger.info("[paperclip] -> #{path}")
+            logger.info("[paperclip] deleting #{path}")
             FileUtils.rm(path) if File.exist?(path)
           rescue Errno::ENOENT => e
             # ignore file-not-found, let everything else pass
@@ -151,7 +149,6 @@ module Paperclip
         base.class.interpolations[:s3_domain_url] = lambda do |attachment, style|
           "#{attachment.s3_protocol}://#{attachment.bucket_name}.s3.amazonaws.com/#{attachment.path(style).gsub(%r{^/}, "")}"
         end
-        ActiveRecord::Base.logger.info("[paperclip] S3 Storage Initalized.")
       end
 
       def s3
@@ -193,10 +190,9 @@ module Paperclip
       alias_method :to_io, :to_file
 
       def flush_writes #:nodoc:
-        logger.info("[paperclip] Writing files for #{name}")
         @queued_for_write.each do |style, file|
           begin
-            logger.info("[paperclip] -> #{path(style)}")
+            logger.info("[paperclip] saving #{path(style)}")
             key = s3_bucket.key(path(style))
             key.data = file
             key.put(nil, @s3_permissions, {'Content-type' => instance_read(:content_type)}.merge(@s3_headers))
@@ -208,10 +204,9 @@ module Paperclip
       end
 
       def flush_deletes #:nodoc:
-        logger.info("[paperclip] Writing files for #{name}")
         @queued_for_delete.each do |path|
           begin
-            logger.info("[paperclip] -> #{path}")
+            logger.info("[paperclip] deleting #{path}")
             if file = s3_bucket.key(path)
               file.delete
             end

test/attachment_test.rb

@@ -599,14 +599,14 @@ class AttachmentTest < Test::Unit::TestCase
                 end
               end
 
-              should "not delete the files saving in a deprecated manner" do
-                @attachment.expects(:instance_write).with(:file_name, nil).never
-                @attachment.expects(:instance_write).with(:content_type, nil).never
-                @attachment.expects(:instance_write).with(:file_size, nil).never
-                @attachment.expects(:instance_write).with(:updated_at, nil).never
+              should "delete the files after assigning nil" do
+                @attachment.expects(:instance_write).with(:file_name, nil)
+                @attachment.expects(:instance_write).with(:content_type, nil)
+                @attachment.expects(:instance_write).with(:file_size, nil)
+                @attachment.expects(:instance_write).with(:updated_at, nil)
                 @attachment.assign nil
                 @attachment.save
-                @existing_names.each{|f| assert File.exists?(f) }
+                @existing_names.each{|f| assert ! File.exists?(f) }
               end
 
               should "delete the files when you call #clear and #save" do

test/paperclip_test.rb

@@ -91,8 +91,6 @@ class PaperclipTest < Test::Unit::TestCase
       end
 
       should "not assign the avatar on mass-set" do
-        @dummy.logger.expects(:debug)
-
         @dummy.attributes = { :other => "I'm set!",
                               :avatar => @file }
         
@@ -101,8 +99,6 @@ class PaperclipTest < Test::Unit::TestCase
       end
 
       should "still allow assigment on normal set" do
-        @dummy.logger.expects(:debug).times(0)
-
         @dummy.other  = "I'm set!"
         @dummy.avatar = @file