astropy/astropy — pull request #434 by eteq (2012-10-15 20:29:15+00:00)
Title: update units default argument

This is quite minor, but if you do ``Unit()`` on the current branch, it gives an error about `None` being an invalid unit because of @mdboom's recent changes to how `units` treats None. This changes `Unit` to just not have a default instead of using an invalid default.