Last-resort removal treated the selected engine's failure to place a lone
part as proof it could not fit with the clamps in place. Rectangles packs
bounding boxes, so a concave part whose material clears a clamp lost that
clamp for nothing (C10). A part now counts as blocked only when the caller's
engine, Irregular (true material, NFP) and Rectangles all fail on every
offered stock; Default already runs both lanes.
PM c5984c6e-3882-4d15-8a42-8de76b4c2080