Don't write original file if it wasn't reprocessed

If `only_process` list is not empty, but it doesn't contain `:original`
style, original file hasn't been reprocessed and it's not needed to
rewrite/reupload it.

[fixes #1993]
[fixes #2046]
[fixes #1804]

lib/paperclip/attachment.rb

@@ -238,6 +238,9 @@ module Paperclip
     # the instance's errors and returns false, cancelling the save.
     # the instance's errors and returns false, cancelling the save.
     def save
     def save
       flush_deletes unless @options[:keep_old_files]
       flush_deletes unless @options[:keep_old_files]
+      if @options[:only_process].any? && !@options[:only_process].include?(:original)
+        @queued_for_write.except!(:original)
+      end
       flush_writes
       flush_writes
       @dirty = false
       @dirty = false
       true
       true

spec/paperclip/storage/s3_spec.rb

@@ -364,6 +364,58 @@ describe Paperclip::Storage::S3 do
     end
     end
   end
   end
 
 
+  context "An attachment that uses S3 for storage and has styles" do
+    before do
+      rebuild_model(
+        (aws2_add_region).merge(
+          storage: :s3,
+          styles: { thumb: ["90x90#", :jpg] },
+          bucket: "bucket",
+          s3_credentials: {
+            "access_key_id" => "12345",
+            "secret_access_key" => "54321" }
+        )
+      )
+
+      @file = File.new(fixture_file("5k.png"), "rb")
+      @dummy = Dummy.new
+      @dummy.avatar = @file
+      @dummy.save
+    end
+
+    context "reprocess" do
+      before do
+        @object = stub
+        @dummy.avatar.stubs(:s3_object).with(:original).returns(@object)
+        @dummy.avatar.stubs(:s3_object).with(:thumb).returns(@object)
+        @object.stubs(:get).yields(@file.read)
+        @object.stubs(:exists?).returns(true)
+      end
+
+      it "uploads original" do
+        @object.expects(:upload_file).with(
+          anything,
+          content_type: "image/png",
+          acl: :"public-read").returns(true)
+        @object.expects(:upload_file).with(
+          anything,
+          content_type: "image/jpeg",
+          acl: :"public-read").returns(true)
+        @dummy.avatar.reprocess!
+      end
+
+      it "doesn't upload original" do
+        @object.expects(:upload_file).with(
+          anything,
+          content_type: "image/jpeg",
+          acl: :"public-read").returns(true)
+        @dummy.avatar.reprocess!(:thumb)
+      end
+    end
+
+    after { @file.close }
+  end
+
   context "An attachment that uses S3 for storage and has spaces in file name" do
   context "An attachment that uses S3 for storage and has spaces in file name" do
     before do
     before do
       rebuild_model(
       rebuild_model(