Distinct keyword is not supported in 1.7.1

I've been trying to get the DISTINCT keyword working with my Google App Engine query.  Turns out that feature isn't available in 1.7.1 which is the version I'm using.  Upgrade to 1.7.4 to get it working.

db.Query(EntityName, projection = ("entityProperty",)).run(distinct=True)
Unknown configuration option ('distinct')

Edit
SDK 1.7.4 release notes
http://code.google.com/p/googleappengine/wiki/SdkReleaseNotes