as `_bucket` is an `unordered_map<bucket_id, timestamp_bucket_writer>`,
when writing to a given bucket, we try to create a writer with the
specified bucket id, so the returned iterator should point to a node
whose `first` element is always the bucket id.
so, there is no need to reference `it` for the bucket id, let's just
reference the parameter. simpler this way.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#20598
028410ba58