        Make a commit on the current or given TopGit-controlled topic
        branch that makes it equal to its base, including the presence or
        absence of .topmsg and .topdeps.  Annihilated branches are not
        displayed by `tg summary`, so they effectively get out of your
        way.  However, the branch still exists, and `tg push` will
        push it (except if given the `-a` option).  This way, you can
        communicate that the branch is no longer wanted.

        When annihilating a branch that has dependents (i.e. branches
        that depend on it), those dependents have the dependencies of
        the branch being annihilated added to them if they do not already
        have them as dependencies.  Essentially the DAG is repaired to
        skip over the annihilated branch.

        Normally, this command will remove only an empty branch
        (base == head, except for changes to the .top* files); use
        `-f` to annihilate a non-empty branch.

        After completing the annihilation itself, normally `tg update`
        is run on any modified dependents.  Use the `--no-update` option
        to suppress running `tg update`.

        The same `--stash` and `--no-stash` options are accepted with
        the same exact semantics as for "tg update".

