Upgrade to 3.0 causing weird behavior - first entry has response but no request?

Support
1

We upgraded our private instances:
WPT 3.0
Agent 3.6.2
We currently host on Amazon (AWS).

We are seeing that the first line of waterfall has no request, and a response that occurs much later than the actual page. Anyone see this? The response seems to indicate a possible P3P issue?

Details:
IP: 216.58.219.36
Error/Status Code: 200
Protocol: HTTP/2
HTTP/2 Stream: 1
Client Port: 61647
Request Start: 0.243 s
Time to First Byte: 0 ms
Content Download: 0 ms
Bytes In (downloaded): 0.4 KB
Bytes Out (uploaded): 0 B

REQUEST IS BLANK

Response:
:status: 200
content-type: text/html; charset=UTF-8
strict-transport-security: max-age=86400
p3p: CP=“This is not a P3P policy! See P3P and Google's cookies - Google Account Help for more info.”
content-encoding: gzip
date: Sun, 05 Mar 2017 13:06:51 GMT
server: gws
cache-control: private
x-xss-protection: 1; mode=block
x-frame-options: SAMEORIGIN
expires: Sun, 05 Mar 2017 13:06:51 GMT
set-cookie: NID=98=(REMOVED for security reasons) expires=Mon, 04-Sep-2017 13:06:51 GMT; path=/; domain=.google.com; HttpOnly
alt-svc: quic=“:443”; ma=2592000; v=“36,35,34”

See attached waterfall

2

Hello
It’s probably an HTTP/2 request that has been PUSHed by the server

3

It turns out both my issues were related to some prewarming functionality in WPT for certain caches. Likely why we only saw it in our 3G tests. It sounds like a race was lost and so we see the response late. Patrick has, most awesomely, provided a patch