`df/problematic-chars` skip/fail (mkdir+df issues)

[drinkcat]

What the GNU test does is something like that:

dd if=/dev/zero of=blob bs=8192 count=200
mkfs -t ext2 -F blob

mnt="$(env printf 'm\xf3unt p\xf3int')"
mkdir "$mnt"
sudo mount -oloop blob "$mnt"

LC_ALL=$LOCALE_FR_UTF8 df --output=target "$mnt"

sudo umount "$mnt"
rmdir "$mnt"

And the output of df should be:

Mounted on
/home/drinkcat/dev/coreutils/coreutils/m?unt p?int

Swapping in components with uutils:

• printf is fine.
• cargo run mkdir "$mnt" works, but creates a different directory:

$ cargo run mkdir "$mnt"
$ mkdir "$mnt"
$ ls -ld m*int
drwxr-xr-x 2 drinkcat drinkcat 4096 Jul 20 20:50 'm'$'\363''unt p'$'\363''int' << created by GNU mkdir
drwxr-xr-x 2 drinkcat drinkcat 4096 Jul 20 20:49 'm�unt p�int' << created by uutils mkdir

• LC_ALL=$LOCALE_FR_UTF8 cargo run df --output=target "$mnt" fails:

error: invalid UTF-8 was detected in one or more arguments

[drinkcat]

I'll look at this one. For mkdir, the problem appears to start here:

 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
    let mut args = args.collect_lossy();

collect_lossy mangles the bytes.