`infer` incorrectly identifies `mkv` as `webm`

[a99984b1799]

Demo:

$ ffprobe example.mkv
...
Input #0, matroska,webm, from example.mkv:
  Metadata:
    ENCODER         : Lavf60.16.100
  Duration: 00:02:46.10, start: 0.000000, bitrate: 42034 kb/s
  Stream #0:0: Video: hevc (Main), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 1k tbn
...

$ cargo run -- example.mkv
Inferred: Ok(Some(Type { matcher_type: Video, mime_type: "video/webm", extension: "webm" }))

Code

fn main() {
    let inf = std::env::args().nth(1).unwrap();
    println!("Inferred: {:?}", infer::get_from_path(&inf));
}

The current code detects two byte patterns. This file doesn't contain the first one:

$ xxd -d example.mkv | head -n1
00000000: 1a45 dfa3 a342 8681 0142 f781 0142 f281  .E...B...B...B..
$ #                 ^ diverges here

And does contain the second one, but at a different offset (24-31 instead of 31-38):

$ xxd -d example.mkv | grep "6d61 7472 6f73 6b61"
00000016: 0442 f381 0842 8288 6d61 7472 6f73 6b61  .B...B..matroska