stable vs. feature releases?

Recently, I wanted to use this date adjustment feature described
in this circa 2005 email thread:
http://www.mail-archive.com/[email protected]/msg33178.html

It turns out that the 1.12.10 release referred to above is
in the 'feature' directory, and not the 'stable' directory
on the web site where the source is distributed:
ftp://ftp.gnu.org/non-gnu/cvs/source/feature/1.12.10/

That 'feature' release was built in July 2005.

How/when is the decision made to transition a release from
'feature' to 'stable'?

This is a relevant question, because various OS distributions
may employ a policy that only 'stable' releases are distributed.