joomla/joomla-platform — pull request #1366 by elinw (2012-07-14 16:36:59+00:00)
Title: There is no reason no to allow blank article bodies.

As discussed on the CMS list there is no reason for this annoying requirement though there may have been in the past.
https://groups.google.com/forum/?fromgroups#!topic/joomla-dev-cms/994z5Pnzvms