Fixes #2725.
As nested FlattenUnordered will be placed into a new future inside of FuturesUnordered every time its inner stream emits an item, its base stream's waker will point to an outdated task, and this will result in an inability to propagate the call properly.
Fixes #2725. As nested
FlattenUnorderedwill be placed into a new future inside ofFuturesUnorderedevery time its inner stream emits an item, its base stream's waker will point to an outdated task, and this will result in an inability to propagate the call properly.