Summary:
To reflect changes in PR https://github.com/facebook/rocksdb/issues/6072
This comment also implies that a seemingly valid use-case for
max_valid_backups_to_open is flawed: even if you only want to add a new
backup without trying to delete, you might need to clean up after a
backup creation that never finished. To clean up properly requires
opening all backups to get proper ref counts on shared files.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6105
Test Plan: code comment only
Differential Revision: D18736716
Pulled By: pdillinger
fbshipit-source-id: 2447c0000eefe3a4ca606926bfe922a8456b0cb7
7e8b4f5f69