Lnav complains about out-of-order messages when sorted on a timestamp different than the syslog reception time

[FaffeF]

I realised the issue I replied to today was closed ten years ago... will open this one instead.

Not quite the same issue, but I would also like to get rid of the 'out-of-order' messages.

I often look at logs that are received from individual machines. They are stored there, and then sent in batches. The timestamp used for sorting is the log generation time, but syslog also stores the log server receive time. The logs are stored in separate files per machine.

This means the individual log files are sorted, but logs may be received quite a while after they are actually produced. Days even, if there's an outage. I guess that Lnav doesn't like this, and complains about the receive time, even though the log events sort fine using the generation time.

Originally posted by @FaffeF in #427