It's seemingly just a timing issue, where the slow Debug bot executes in a different order. This results in one of the "PASS" messages appearing *before* the successfully parsed message. See referenced URL. I'm marking it flaky on the bot.
Created attachment 182604 [details] Patch
Comment on attachment 182604 [details] Patch Thanks Tony!
Comment on attachment 182604 [details] Patch Clearing flags on attachment: 182604 Committed r139636: <http://trac.webkit.org/changeset/139636>
All reviewed patches have been landed. Closing bug.
Removed the TestExpectations entry in r139637.