Fix crash in annotator if the line is '@@@'.
Fix crash in annotator if the line is '@@@'.

R=smut@chromium.org, stip@chromium.org
BUG=349813

Review URL: https://codereview.chromium.org/219403007

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@260699 0039d316-1c4b-4281-b951-d872f2087c98

shishkander/recipes-py,luci/recipes-py,shishkander/recipes-py,luci/recipes-py