thoughtbot/paperclip — pull request #1178 by tardate (2013-02-28 10:08:25+00:00)
Title: use nil_adapter when attachment = ""

In Rails after the 3.2.11 update, when a form with file upload field is submitted without an attachment, the attachment attribute is now passed in the params as "". This causes a 'No handler found for ""' exception in Paperclip.

This commit coerces a '' attachment to the NilAdapter and resolves the problem.