TypeError: content.once is not a function
    at Multipart._pushFile (multipart.js:86)
    at Multipart._maybeDrain (multipart.js:50)
    at Multipart._transform (multipart.js:42)
    at Multipart.Transform._read (_stream_transform.js:184)
    at Multipart.Transform._write (_stream_transform.js:172)
    at doWrite (_stream_writable.js:428)
    at writeOrBuffer (_stream_writable.js:417)
    at Multipart.Writable.write (_stream_writable.js:334)
    at eachSeries (send-files-stream.js:51)
    at withoutIndex.js:9