3 branches: stable, staging, experimental

The current release is the head of stable.

Everything approved for the next release is in staging

All the patches that might get pulled into staging before it becomes stable are in experimental. This is good because you find out early if two patches conflict with each other (in the "they break each other" sense, not in the VCS meaning of conflict), but unstable stuff doesn't pollute your staging branch.

When a release happens, you destroy the experimental branch and recreate it from the new staging branch. Anybody who wants their patches that didn't make the cut for the release has to rebase them onto the new experimental branch.