do not call ngx_http_file_cache_free() if a response is not cacheable
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 157c5fd..7e0c72a 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2749,7 +2749,7 @@
 
 #if (NGX_HTTP_CACHE)
 
-    if (r->cache) {
+    if (u->cacheable) {
         time_t  valid;
 
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,