cache is insensitive to `Accept`/`Content-Type`

The cache doesn't consider the Accept request header. In some rare edge cases this can lead to the wrong format being sent.

repro steps:

# first query priming the cache
curl https://lindas-cached.test.cluster.ldbar.ch/query -H 'Accept: application/n-quads' --data-raw 'query=DESCRIBE%20%3Chttps%3A%2F%2Fld.admin.ch%2Fcanton%2F2%3E'

# second query reusing the cache - but delivering the wrong format
curl https://lindas-cached.test.cluster.ldbar.ch/query -H 'Accept: application/n-triples' --data-raw 'query=DESCRIBE%20%3Chttps%3A%2F%2Fld.admin.ch%2Fcanton%2F2%3E'

varnish-post/config/default.vcl

Lines 73 to 86 in 2613fb0

    
           # Alter the hashing method to include POST bodies 
        
           # See: https://docs.varnish-software.com/tutorials/caching-post-requests/#step-3-change-the-hashing-function 
        
           sub vcl_hash { 
        
             hash_data(req.http.Authorization); 
        
             hash_data(req.url); 
        
             if (req.http.X-Body-Len) { 
        
               bodyaccess.hash_req_body(); 
        
             } else { 
        
               hash_data(""); 
        
             } 
        
             return (lookup); 
        
           }

	# Alter the hashing method to include POST bodies
	# See: https://docs.varnish-software.com/tutorials/caching-post-requests/#step-3-change-the-hashing-function
	sub vcl_hash {
	hash_data(req.http.Authorization);
	hash_data(req.url);

	if (req.http.X-Body-Len) {
	bodyaccess.hash_req_body();
	} else {
	hash_data("");
	}

	return (lookup);
	}