+ (unlink-blocks b block)
+ ;; In bug 147 the almost-all-blocks-have-a-successor invariant was
+ ;; broken when successors were deleted without setting the
+ ;; BLOCK-DELETE-P flags of their predececessors. Make sure that
+ ;; doesn't happen again.
+ (aver (not (and (null (block-succ b))
+ (not (block-delete-p b))
+ (not (eq b (component-head (block-component b))))))))