Incorect filename in Content-Disposition using bytesPart

[danhandrea]

Using bytesPart in a multipartBody will always set the filename in Content-Disposition to "blob" even though bytesPart used with correct parameters.

Http.bytesPart "picture_name.jpg" "image/png" bytes

will become Content-Disposition: form-data; name="picture_name.jpg"; filename="blob"