Comment # 8 on bug 943757 from Stefan Hundhammer

It's been a long time... ;-)

I faintly remember that redirecting all stderr output to the y2log tends to
mess up the y2log badly as there are different levels of buffering all over the
place. libyui has its own thread-safe logger with its own logging buffer. If
some other output is writing to the same file handle, but bypassing that
thread-safe log buffer, the output will become mixed, disregarding things like
output lines (and of course the y2log line header with the timestamp, PID,
source file, function, source line number).

IIRC we used that for a short while and then became frustrated quickly because
the logs were messed up in the most critical moments.

There is no easy way around this; IIRC I tried to come up with a strategy to
route that output through the thread-safe libyui logger, but if a process
simply writes to a file handle, there is no reliable way to do this.

Another approach might be to simply open yet another file dedicated to stderr
output. Of course that implies taking care of log rotation etc.; that's
probably the reason why back then we had decided to redirect it to /dev/null.
That output just wasn't that important.