This patch moves the difference between two mutation_partition's
row_tombstones inside the range_tombstone_list.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This class is responsible for representing a set of range tombstones
as non-overlapping disjoint sets of range tombstones.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>