Currently, partitioned_sstable_set::insert may erase a sstable
from the set inadvertently, if an exception is thrown while
(re-)inserting it.
To prevent that, simply return early after detecting that
insertion didn't took place, based on the unordered_set::insert
result.
This issue is theoretical, as there are no known case
of re-inserting sstables into the partitioned sstable set.
Fixes#14060
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closes#14061
c685ef9e71