In the server code, there are instances where multiple sessions are used in a single thread. If these nested sessions do not use the cache_max_wait_ms=1 config option, they can completely stall cache eviction, as demonstrated in SERVER-61097. Rather than introducing a mechanism in the server to enforce that nested sessions use cache_max_wait_ms=1, we can depend on the new rollback event handler to asynchronously rollback conflicting sessions.