upgraded the nginx core to 1.9.15.

patches/nginx-1.9.15-hash_overflow.patch

@@ -0,0 +1,20 @@
+# HG changeset patch
+# User Yichun Zhang <agentzh@gmail.com>
+# Date 1412276417 25200
+#      Thu Oct 02 12:00:17 2014 -0700
+# Node ID 4032b992f23b054c1a2cfb0be879330d2c6708e5
+# Parent  1ff0f68d9376e3d184d65814a6372856bf65cfcd
+Hash: buffer overflow might happen when exceeding the pre-configured limits.
+
+diff -r 1ff0f68d9376 -r 4032b992f23b src/core/ngx_hash.c
+--- a/src/core/ngx_hash.c	Tue Sep 30 15:50:28 2014 -0700
++++ b/src/core/ngx_hash.c	Thu Oct 02 12:00:17 2014 -0700
+@@ -312,6 +312,8 @@ ngx_hash_init(ngx_hash_init_t *hinit, ng
+         continue;
+     }
+ 
++    size--;
++
+     ngx_log_error(NGX_LOG_WARN, hinit->pool->log, 0,
+                   "could not build optimal %s, you should increase "
+                   "either %s_max_size: %i or %s_bucket_size: %i; "