Invalid YUV output (relative to aomdec)

To reproduce:

# dump the bitstream as "input.ivf"
echo "REtJRgAAIABBVjAxCAAIAAcAAAABAAAAAwAAAAAAAABgAAAAAAAAAAAAAAASAAoKAAAAARf8D7+YBBoIFAAAAMAFVIAiRhVbrrJLzwZhDFvtv90AFbZ9S3Qmf/9e7encpX6Hrsd1I6aK1V9S35FNxaykdyKaWbdn7bp+KgwpS1sYe6BGEGKRPpPlVYBpAAAAAQAAAAAAAAASABogOgACAggAAAAAAAAAAAAQABAADAAIAAUAAwAAjgAqoAQiQwC4PpNhC4oD4FVvmv8FXB////+rkux+QglyTl1GVVlVZVWUTmVGVUF2+xKH///Rm6SOAYQaRDEhZEMTDEpB3nz1J6xdAAAAAgAAAAAAAAASABogOgAEBAQAABAAAAAAQAAAAEgALAAYAA0ABwACjgAqoAQiNwC4PpOIS69JYuTJpOLULj/CUO/jQRGf////////ijZvvRXuw0uOrWaRsCDawjNPaJDC6G6tRyA=" | base64 -d > input.ivf
aomdec -o ref.y4m input.ivf
dav1d -q --demuxer ivf -i input.ivf -o dec.y4m
# convert to yuv before diff
ffmpeg -loglevel 1 -i dec.y4m -y dec.yuv
ffmpeg -loglevel 1 -i ref.y4m -y ref.yuv
diff -q dec.yuv ref.yuv

Results:

Files dec.yuv and ref.yuv differ

Here's what the diff looks like:

Ref:

00000040  ff ff ff ff ff ff 00 00  00 00 00 00 00 ff ff ff  |................|
00000050  ff ff ff ff 00 00 00 00  00 00 00 ff ff ff ff ff  |................|

Decoded from dav1d:

00000040  ff ff ff ff ff ff 00 17  47 00 28 00 00 ff fb ff  |........G.(.....|
00000050  ff ff ff ff 00 00 15 0d  0f 16 00 ff ff ff ff ff  |................|