I have just upgraded to 2.9 alpha on my test box which has asterisk 1.8 installed.
The upgrade went smoothly except for the Set Caller ID third party addon. Everything happens as expected to upgrade from 2.8.2 to 220.127.116.11 and it appears that the module has been upgraded, however, the module still shows as 2.8.2 and after a Check on Line the module is back in red ready for upgrade. The same thing happens again if you try to upgrade it again.
Initial checks indicate that things are functional, so far so good!