Register Alacritty shells as tty sessions on macOS

Unless the `shell` config is specified, launch the user's shell with:

```sh
login -flp $USER /bin/sh -c "exec -a -shell /path/to/shell"
```

On macOS, just running a shell prefixed by `-` is not sufficient to be
registered as a login session for things like `w` and `logname`.
However, using the `login` command changes the directory to `$HOME`
before running the program by default, which is not desired. The `-l`
flag disables this behavior, but also skips prepending `-` to the
executed program, so shells will not run as login shells. Instead we
just do this part ourselves with `exec -a`. The result is login shells
that run in the intended directory and are registered as tty sessions.

Fixes #3420.

0 files changed, 0 insertions, 0 deletions