Not sure why they were disabled, although im sure they could be nefarious. Would help making mirrors like from LinuxCafeFederation/awesome-alternatives#7 work again since we can use a post receive hook to send a git --mirror command over.
Not sure what you mean, it might either be:
Which one did you have in mind?
git --mirror makes most sense in a client-side hook, like for example
Alternatively defining+registering a custom git subcommand or shell alias?
Deleting a branch is permanent. It CANNOT be undone. Continue?