When the `hub.hookscript` git configuration is present, it will be used as a script to run on certain events. For now this feature is considered experimental and only the `postclone` event is defined. Please have a look at the `HOOK SCRIPT` section in the man for details. The old `master` default made little sense, as repositories sometimes have a different default branch, or have no `master` at all. Now that GitHub have changed the default branch to `main` for new projects (and many projects are moving away from using `master` as a name for anything altogether) it makes less sense that ever to use this last resort default. An error will be shown if the `pull new` or `pull attach` commands have no remote tracking branch or a `hub.pullbase` configuration is present. If you relied on this behaviour just do: `git config hub.pullbase master` (add `--global` to set this default globally for all your repos).