The RFC doesn't have a method for a set-if-not-exists (SETNX) call.
Earlier versions of this document specified the uses of PUT for set operations, and defined this as having upsert semantics. The POST verb is now used for upsert, and PUT is reserved for future set-if-does-not-exist semantics (similar to Redis's SETNX operation).
This task is to check if this is needed now, or ever.
- checked MediaWiki code to see if we set different session TTLs for different sessions within a wiki for some reason
- checked if we have session TTLs set at different values for different wikis