Code review comment for lp:~thumper/juju-core/fix-backlog-limits

Due to the buffered i/o in the tailer, I'd prefer to keep the line
parsing functionality in the server side.

However I think that axw's approach of breaking out the backtracking is
a good one, and that is the approach I'll use.

https://codereview.appspot.com/85570045/