malformed overview! batches

[Olaf Titz]

> What if the last byte/word of every line was a checksum
> then the receiving end of the pipe could detect these fragmented
> lines and either not log them, or do something special with them.

That helps to _detect_ corrupted lines, but especially in the case of
overchan (like with innfeed) corrupted lines effectively mean lost
articles and therefore we rather want to _avoid_ them.

A possible way would be to buffer one "message" to the channel and in
case of spooling, write the whole message (i.e. header, in case of
overchan; line, otherwise) again to the spool file. I don't know how
complicated that would be.

Another thought is to ask the kernel how much space is in the pipe buffer
before attempting to write to it. I suspect that is highly non-portable.

Olaf