Fix of the previous commit: is_directio flag processing introduced in r4077
is still worthwhile.

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 1306d14..0d605b5 100644
--- a/src/core/ngx_open_file_cache.c
+++ b/src/core/ngx_open_file_cache.c
@@ -288,6 +288,8 @@
                     file->use_event = 1;
                 }
 
+                of->is_directio = file->is_directio;
+
                 goto update;
             }