As of today (Jan 05) the builds of Jenkins core deployed in Code Valet are starting to log "Collision detected. timestamp=1515197742000, expected=1515193821000 "
It's unclear to me why this is happening but this log message has never been spotted before in Code Valet and is starting to crop up on completely idle master instances.
I think this might be a "canary" chirping that something is wrong with some recent changes in master but I haven't the slightest idea what they might be. Perhaps oleg_nenashev knows?
Oleg, I'm temporarily assigning this to you. Would you mind double-checking to see if any of the recent Remoting changes could be related to this?
If not, feel free to re-assign it back and I'll keep hunting :-/