fbthrift (facebook thrift) stable release?

Regarding the RPC package "thrift":

I believe this package exists in two forms: the "classic" Apache Thrift, and the somewhat newer "Facebook thrift" (or fbthrift).

I believe that Apache Thrift does not support asynchronous clients which make call that return immediately, coupled with a callback mechanism to notify the client that the server has completed its work. (My previous question, titled "thrift async c++ example" yielded a response confirming this belief).

I believe that fbthrift does a good job in supporting these things, particularly in C++ (and its C++11 variant).

However... my efforts to work with fbthrift led me to conclude that it is unstable as it's being changed pretty frequently.

Does anyone know whether there are stable "point releases" of fbthrift, and if so, how I can access them?