#[files] produces incorrect test names on Windows

[GermanCoding]

Steps to reproduce

1. cargo new reproducer && cd reproducer && cargo add --dev rstest
2. main.rs

fn main() {
    println!("Hello, world!");
}

#[cfg(test)]
mod test {
	use rstest::rstest;
	use std::path::PathBuf;
	
	#[rstest]
	fn wrong_testname(#[files("src/main.rs")] _p: PathBuf) {}
}

3. Run this test on Linux & Windows. Compare names of the generated test cases.

Expected output

cargo test

running 1 test
test test::wrong_testname::_p_1_src_main_rs ... ok

This is what happens when running on Linux.

Actual output

However, when running on Windows 11, this happens:

cargo test

running 1 test
test test::wrong_testname::_p_1__UP_D_Rust_projectsreproducersrcmain_rs ... ok

The test seems to use the full path up from the drive's root, not from the crate's base directory. It is also missing some _ in place of path separators.