visionmedia/superagent — pull request #322 by luman75 (2014-02-19 16:02:15+00:00)
Title: Support for content-type for the attachments.

The proposed changes add possibility to specify content types to the attached files.
Something like this:

request.post(url)
.query(reqPar)
.attach(field, file, filename, contenttype)
.end (res) ->

where contenttype is just a content type text like "image/jpeg" or something else.
Sometimes you cannot trust on filename extensions.