I would like to use Nginx to retrieve pages placed in a memcached bin by Drupal caching.

The Drupal key appears to be:

cache_page-http%3A%2F%2Fexample.com%2Fcontent%2Fquadrum-utinam

Using

...
set $memcached_key cache_page-$scheme://$host$uri;
memcached_pass 127.0.0.1:11211;
...

does not produce a match. I get:

key: "cache_page-/content/quadrum-utinam" was not found by memcached while reading response header from upstream ...

Is that an encoding problem?