Fix btree `CursorMut::insert_after` check Fixes a check inside `BTreeMap`'s `CursorMut::insert_after`, where it would peek the previous element to check whether the inserted key is below the next one, instead of peeking the next element.
Fix btree `CursorMut::insert_after` check Fixes a check inside `BTreeMap`'s `CursorMut::insert_after`, where it would peek the previous element to check whether the inserted key is below the next one, instead of peeking the next element.