Buffer fails because a start turn is discarded

[barendgehrels]

With this wkt:
MULTIPOLYGON(((2 8,2 9,3 8,2 8)),((7 1,7 2,8 1,7 1)),((5 2,5 3,6 2,5 2)),((2 2,2 3,3 3,2 2)),((1 3,1 4,2 4,1 3)),((6 4,6 5,7 4,6 4)),((9 8,8 8,9 9,9 8)),((9 8,9 7,8 7,9 8)))

And with miter, buffer distance 1.0 (as in recursive_polygons_buffer.cpp where this case comes from)

There is one turn discarded because it is a start turn.

See next picture, turn 0 is discarded because of 1 - but it should not.