test ngx_file_info() result, the bug has been introduced in r2070

src/core/ngx_open_file_cache.c

diff --git a/src/core/ngx_open_file_cache.c b/src/core/ngx_open_file_cache.c
index f9c6a45..60a8368 100644
--- a/src/core/ngx_open_file_cache.c
+++ b/src/core/ngx_open_file_cache.c
@@ -457,7 +457,7 @@
             goto failed;
         }
 
-        if (of->is_dir) {
+        if (ngx_is_dir(&fi)) {
             goto done;
         }
     }