Ensure split chunks are written as binary to avoid errors such as Enc…

…oding::UndefinedConversionError: "\x89" from ASCII-8BIT to UTF-8

lib/x/media_uploader.rb

@@ -72,7 +72,7 @@ def split(file_path, chunk_size)
         File.open(file_path, "rb") do |f|
           while (chunk = f.read(chunk_size))
             file_paths << "#{Dir.mktmpdir}/x#{format("%03d", file_number += 1)}".tap do |path|
-              File.write(path, chunk)
+              File.binwrite(path, chunk)
             end
           end
         end