We have multiple servers and they all use the same S3 bucket, xmlsitemap-rebuild generates a folder with a unique hash, the hash changes based on the host it seems, when server b looks for the files it looks for its own hashed folder, therefore doesn't appear to share generated files across hosts, requiring a rebuild to be run on all hosts.
I think we should have a $conf['xmlsitemap_single_hash'] = true; (needs better name) or just change the behavior to have one hash.
Also I have been wondering, what is the reason we save to filesystem at all? Why can't we just serve the /sitemap.xml path out of the DB?