How to follow request path within the config?

[cachito]

Hello, I'm hitting my head against a wall since a couple days ago. Last
paragraph has the big question, the rest is context.

I run a fairly big Wordpress blog, with a somewhat convoluted configuration
rewriting legacy URLs that follow me since 2002. I use extensive caching via
plugins that pregenerate HTML on disk and I rewrite requests to serve HTML
instead of talking to PHP. Everything worked well until a domain change.

Yesterday after I replaced the domain in the various configuration files,
nginx started sending every request to the PHP processor. The location / is
pretty standard:
location / {
try_files cache_path$uri $uri $uri/ /index.php;
}

Everything in the paths exists and has the correct permissions, but nginx
keeps sending everything through /index.php and killing my server via a
180-200 load average.

I tried everything googleable, but I can't detect WHY nginx goes that route.
The debug log shows a lot of not matching rules/regexes but there's nothing
I can do to follow the decision tree that nginx follows to end in PHP. Is
there anything I can do to at least simulate the directive processing?

Thanks in advance.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,254690,254690#msg-254690