dd of=/dev/stdout cause Illegal seek

[oech3]

$ dd if=/etc/pacman.conf of=/dev/stdout
dd: failed to seek in output file: Illegal seek

GNU shows the content of input.
Maybe, caused by

coreutils/src/uu/dd/src/dd.rs

Lines 1440 to 1452 in 877f656

	/// Canonicalized file name of `/dev/stdout`.
	///
	/// For example, if this process were invoked from the command line as
	/// `dd`, then this function returns the [`OsString`] form of
	/// `"/dev/stdout"`. However, if this process were invoked as `dd >
	/// outfile`, then this function returns the canonicalized path to
	/// `outfile`, something like `"/path/to/outfile"`.
	fn stdout_canonicalized() -> OsString {
	match Path::new("/dev/stdout").canonicalize() {
	Ok(p) => p.into_os_string(),
	Err(_) => OsString::from("/dev/stdout"),
	}
	}

?

[pixelb]

Same thing happens with /dev/tty