One of the challenges in diagnosing HELP-51094 / HELP-51359 was the inability to identify from the mongod logs which mongos had been used to send the command that ultimately crashed the mongod. This is because the mongod logs for the offending connection (thread) would only contain a "client metadata" log message followed later by a "BACKTRACE" log message with no other messages in between. Adding the mongos host and port to the context logged by the "client metadata" message would have made it simpler to look specifically at that particular mongos logs and FTDC for more clues.