Are HTML Comments indexed by Google? Maybe Yes!

There seems to be a wide range of answers to it, ranging from:

"Commented tags are commented out - so by nature, no. Bots ignore them. They are just to help the programmers understand what the muck they did and why."

to

"Simple answer: use this URL and you clearly will find pages containig the text "Served by srv168" as interpreted HTML comment."

So, whats right? What's the rule for Google?

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miblofoxtra = "alert('X');"