Pylons/colander — pull request #199 by ltvolks (2014-11-26 23:48:51+00:00)
Title: Allow String type to optionally deserialize empty strings

- Added optional keyword argument `allow_empty` to `colander.String`
schema type. When True, deserializes an empty string to an
empty string. When False (default), an empty string deserializes to
`colander.null`.

I think this satisfies and supercedes https://github.com/Pylons/colander/pull/146.