Sync with react-addons-css-transition-group?

As far I understand preact-css-transition-group is based on react-addons-css-transition-group. I guess not the latest version.

I'm currently investigating issues similar to https://github.com/facebook/react/issues/1707.
Not sure, maybe it's not problem of preact-css-transition-group at all. Anyway, it would be beneficial to know how merge is done and how often. So I have couple of questions regarding that.

When was last sync with react-addons-css-transition-group?
Is there any procedure or how often is sync done?
How can I get version react-adddon-css-transition-group that preact version is based on?

Is hard to compare by commit ids as code structure seems to be bit different to current version of react-addons-css-transition-group