“CAUTION: provisional headers are shown” in Chrome debugger

Question

I noticed a strange caution message when looking at downloaded resources using Google chrome inspector (F12):

Caution provisional headers a

Answer 1

HTTP/2 Pushed resources will produce Provisional headers are shown in the inspector for the same theory as @wvega posted in his answer above.

e.g: Since the server pushed the resource(s) to the client (before the client requested them), the browser has the resources cached and therefore the client never makes/needs a requests; So because...

...the real headers are updated when the server responds, but there is no response if the request was blocked.