Attachments do not work in 1.1.5

[commilfo]

I've just spent a lot of time investigating why sending emails with attachments fails.
You already have a working fix but it's not a part of the current 1.1.5 version.
Please either release 1.1.6 or mention in the documentation that attachments don't work.
Thanks!

[luflow]

Is there a possibility to backport the fix to the old code base to be compatible with older celery versions?

Or where do I find the fix mentioned in your question @commilfo