The code that inserts into the bucket catalog has a potential segfault in presence of concurrent DDL operations.

The code wrongly assumes that by preserving a reference to the CollectionCatalog the subsequent Collection * will remain valid.

Under normal circumstances this would be true if we didn't open a WT snapshot and there were no concurrent DDL operations on that namespace. However, the code then proceeds to perform an acquisition which will establish a snapshot. As a result, the subsequent catalog lookup can return an Opened Collection which has its lifetime tied to the snapshot if there are concurrent DDL operations on that namespace.

Once the acquisition goes out of scope the snapshot would then get released and the opened collection free'd, making the pointer invalid.