git does not wait on hook exes (^C)

From: Anthony Sottile <asottile@umich.edu>
Date: Feb 20, 2020, 21:14 UTC
Message-ID: <CA+dzEB=jJEkuvcX5qDfeXS=mbJu_m=-yUsmHd_KrKAXC3YDe7w@mail.gmail.com>

Here's a small example:

```bash
#!/usr/bin/env bash
foo() {
    echo zzz part 2
    sleep 1
    echo exiting now
}
trap foo SIGINT

echo zzz part 1 sleep 10 ```

```console $ git --version git version 2.25.GIT $ git commit --allow-empty -m foo zzz part 1 ^Czzz part 2

$ exiting now ```

- I pressed ^C during the first sleep
- control was returned back to my terminal
- the hook script was still running in the background

Anthony