The answer to your question is shown in the history in ... Bionic Reference - Terms - Links
... as 2012.02.10
There was a lot of confusion around 5.9.901
and the "leaks" right before 5.9.901
was the first time they pushed a non-release to a collection of users who had not sighed up for the soak test.
(Since I only have my memory to rely on 5.9.902
late documentation ... I deleted the reference.)