date: --file flag outputs different date on EOF of empty file in stdin mode

uutils:
```
$ cargo run date --file -
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.12s
     Running `target/debug/coreutils date --file -`

Thu Sep 10 10:33:53 PM EEST 2026
```

GNU:
```
$ date --file -

Thu Sep 10 12:00:00 AM EEST 2026
^C

```