Repeating the last log lines of the failing build is not necessarily a bad thing, for example when you're using --keep-going (since then the original error may have scrolled past a long time ago).

I'm afraid I have to disagree here: at least in my experience the majority of errors occurs before the last 10 log-lines, that's one of the reasons why I almost always use -L.

Would it be a compromise in your opinion to only enable such a behavior if --keep-going is not set?

That may be true but in that case we should just get rid of the printing of the last few lines entirely (and just say something like "derivation X failed; run nix log X to see the build log").

So you'd be fine with removing the "last N log lines"-feature? (Please note that I only care about it, if -L is set as I get regularly confused with having several lines duplicated when having a failed build).

Yes, sounds good to me.

Just discovered that this can be done by setting the log-lines option, so this can be closed IMHO.

@edolstra should we still remove the functionality (or set log-lines by default to 0)?