- Fix nginx-side flow so we handle .pagespeed. resources ok
when they will land on a customized 404 internal location.
- Additionally, check for a wiped request context and make sure
we do not dereference a null pointer, which is what hurt in
the flow we entered above as the IPRO lookup still was
generating events while the nginx side request context was
gone.
- Also, as a preliminary measure, do not check fail when we
receive a stale event originating from a NgxBaseFetch that
is no longer associated with our request context.
Do log a warning so we'll hear about this happening either
through system test failures or a bug report.
Fixes https://github.com/pagespeed/ngx_pagespeed/issues/1081
Otto van der Schaaf
1964ef5219