Fixes a race condition in disjoint_set::all_compress(). Previously when a rank received a parent query, it would use the status of its query of the item's parent to determine whether to hold onto response. The item's parent could have been updated to the root already while another item held locally was waiting on a query directly to the root, causing the incoming query to be erroneously held onto.
Fixes a race condition in disjoint_set::all_compress(). Previously when a rank received a parent query, it would use the status of its query of the item's parent to determine whether to hold onto response. The item's parent could have been updated to the root already while another item held locally was waiting on a query directly to the root, causing the incoming query to be erroneously held onto.