thoughtbot/paperclip — pull request #1354 by anderslemke (2013-10-07 10:58:42+00:00)
Title: Preserve files when reprocessing

When using S3 for storage, their data consistency model makes the
current behaviour of Attachment#reprocess! unreliable.

Apparently, Amazon can not guarantee that PUT's called after DELETE's
is actually executed in that order.

Hence, I propose preserving files, when doing a reprocces.