Development is discussed on the emacs-devel mailing list.
-Sometime before the release of a new major version of Emacs a "feature
-freeze" is imposed on the trunk, to prepare for creating a release
-branch. No new features may be added to the trunk after this point,
-until the release branch is created. Announcements about the freeze
-(and other important events) are made on the emacs-devel mailing
-list under the "emacs-announce" topic, and not anywhere else.
-
The trunk branch is named "master" in git; release branches are named
"emacs-nn" where "nn" is the major version.