It can be seen as the equivalent of a "development branch" that most other projects have.
On November 25, 2007, patch-34 of the main 22.1.8 development branch was committed.
Louis: We've started a development branch to work on this problem.
In that case, you may find this development branch interesting.
There are two development branches for fli4l, a stable and a development version.
It is often used when a development branch must be up to date with, and yet divergent from, its trunk.
Often, the version that will eventually become the next major version is called the development branch.
There won't be any updates to this development branch either.
In particular, before each release of the parent distribution, its primary development branch is frozen.
They also have an external development branch that funds and provides support for a wide variety of games.