git hack <branch>

The hack command ("let's start hacking") creates a new feature branch with the given name off the main branch and brings all uncommitted changes over to it. Before it does that, it syncs the main branch to ensure commits into the new branch are on top of the current state of the repository.

Variations

If the repository contains a remote called upstream, it also syncs the main branch with its upstream counterpart. You can control this behavior with the sync-upstream flag.

If push-new-branches is set, git hack creates a remote tracking branch for the new feature branch. This behavior is disabled by default to make git hack run fast. The first run of git sync will create the remote tracking branch.