Interesting. It looks like if you want to use enum in 2.7 you have to use a package called flufl[1].
[1] http://bazaar.launchpad.net/~barry/flufl.enum/trunk/view/hea...
[1] http://bazaar.launchpad.net/~barry/flufl.enum/trunk/view/hea...
We may create a almost-compliant back-port for 2.7 as an external library though