fix nonfunctional test case
Fix off-by-one error in log chunk handling

The extra `- 1` here caused single blank lines to be skipped when
chopping un-requested lines of the end of a response.  Earlier tests,
even if they had actually been running, would not have discovered this
as they did not test blank lines.  Fixes #3101.
Merge pull request #1436 from djmitche/bug3101

Fix off-by-one error in log handling of blank lines