Just an FYI, I did make the above changes in directory.py and deleted the memberships_cache file and re-ran the server.
I still did not get the memberships for uuid "cdaboo"
I did print logs after if True to make sure it gets called.
I will investigate more but here is the relevant console output of server
2014-12-05 15:40:18-0800 [-] [caldav-0] [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Acquired lock
2014-12-05 15:40:18-0800 [-] [caldav-0] [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving list of all proxies
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 4 proxies
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving group hierarchy from directory
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group06
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group05
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group04
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group03
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group02
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group01
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] group07
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] ------------------------------------
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] disabledgroup
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 8 groups retrieved from the directory
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 2 groups are proxies
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 6 users delegated-to via groups
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Taking snapshot of group memberships to /Users/gauravjain/development/calendar/CalendarServer-5.2.2/data/Data/memberships_cache
2014-12-05 15:40:18-0800 [-] [caldav-0] [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Storing 6 group memberships in memcached
2014-12-05 15:40:18-0800 [-] [caldav-0] [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Releasing lock
2014-12-05 15:40:18-0800 [-] [caldav-0] [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Group memberships cache updated