boto/boto — pull request #2850 by imtapps (2014-12-30 22:48:23+00:00)
Title: Set version_id to None when 'null' is returned from s3

Currently, when versioning is turned on or suspended for an s3 bucket
calling `key.generate_url` will include a `versionId=null` when the key
in question returns 'null' from s3 as the version id. This will cause
a 403 when trying to use it.