RDP persistence issue using MSTSHASH

[Emeric Brun]

Some of our customers recently encounter issues using MSTSHASH for 
persistence on RDP

Our colleague of Loadbalancer.org are ine the same case and have done a 
nice investigation with unhappy end:

http://blog.loadbalancer.org/microsoft-drops-support-for-mstshash-cookies/

Now, using a session broker/directory seems to be the only way to insure 
persistence on RDP.