autotest: Add a line of logging to ping output parsing

I got an error related to not being able to convert parsed ping output
to floats, and I want to make sure that things like this are easy to
debug for automated runs.

TEST=None
BUG=None

Change-Id: I2797dd4b50578fbed69151501f9070e816dddf88
Reviewed-on: https://gerrit.chromium.org/gerrit/61576
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
1 file changed