rdf2hdt produces invalid UTF8 values?

[KonradHoeffner]

I'm working on an HDT library in Rust and use HDT files produced by hdt-cpp as test input.
Until now that worked fine but I get an error with the subject http://dbpedia.org/resource/Özgür_Özata, which is the last subject in the attached turtle file.
When looking at that file with a hex editor, "Özgür_Özata" is represented as 0xc3,0x96,0x7a,0x67,0xc3,0xbc,0x72,0x5f,0xc3,0x96,0x7a,0x61,0x74,0x61.
These hex values are for example a valid input for the Rust function std::str::from_utf8().
However rdf2hdt changes the first byte from 0xc3 to 0x9d, which causes std::str::from_utf8() to panic.
I'm not an UTF8 expert and can't say whether that is an alternative valid representation of an "Ö" character but given that the function panics I assume it is not so I want to want to submit this as a possible bug.

I'm using a Docker image built from newest commit of the develop branch.

persondata_en_10k.ttl.zip

docker build . -t hdt
docker run -it --entrypoint /bin/bash -v $PWD:/data hdt
cd data
rdf2hdt -f turtle persondata_en_10k.ttl persondata_en_10k.hdt

[KonradHoeffner]

use std::str;

fn main() {
    let hex = [0xc3,0x96,0x7a,0x67,0xc3,0xbc,0x72,0x5f,0xc3,0x96,0x7a,0x61,0x74,0x61];
    let s = str::from_utf8(&hex[0..]).unwrap();
    println!("{s}");
    let hex = [0x9d,0x96,0x7a,0x67,0xc3,0xbc,0x72,0x5f,0xc3,0x96,0x7a,0x61,0x74,0x61];
    let s = str::from_utf8(&hex[0..]).unwrap();
    println!("{s}");     
}

 Compiling hex v0.1.0 (/home/konrad/tmp/hex)
    Finished dev [unoptimized + debuginfo] target(s) in 0.10s
     Running `target/debug/hex`
Özgür_Özata
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Utf8Error { valid_up_to: 0, error_len: Some(1) }', src/main.rs:8:39
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace