Git branch deletion not based on HEAD branch anymore

Hello,

I have noticed that in the "latest" versions of git, `git branch -d branch` instead of refusing to delete a branch that hasn't been merged to HEAD, it now throws a warning and deleting the local branch if it's present in a remote.

Example: ```

warning: deleting branch 'command-runner' that has been merged to
         'refs/remotes/origin/command-runner', but not yet merged to HEAD.
Deleted branch command-runner (was 1716ed5).
```

After diving in git blame for a while I have realized that "lately" refers to a commit done in 2009.

Because the change is over 7 years old, I will explain what is my use case.

The workflow I follow since I started with git is to start an exact replica of my working environment in a personal fork. Anything deleted locally is deleted remotely and viceversa. This allows me to move between work and home smoothly. I also use the default `git config push.default matching`

My typical day starts and ends pulling master from the central repo, and `git branch -d`-ing all the branches I have in local. git would delete the ones that have been merged, and leave alone the ones that have been not been merged. Then I rebase all my branches and push the new master and rebased branches. Because all my local branches track my personal repo, all of them get deleted if I execute my scripts.

I understand it's not possible / convenient anymore to go back, but would it be possible to have an option such as `--merged` to support the old usecase?