bugfix: respect max retry after using balancer pool.

Signed-off-by: tzssangglass <tzssangglass@gmail.com>

patches/nginx-1.27.0-balancer_pool_max_retry.patch

@@ -0,0 +1,27 @@
+diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
+index d04d91e..397cb08 100644
+--- a/src/http/ngx_http_upstream.c
++++ b/src/http/ngx_http_upstream.c
+@@ -4378,6 +4378,9 @@ ngx_http_upstream_next(ngx_http_request_t *r, ngx_http_upstream_t *u,
+     if (u->peer.cached && ft_type == NGX_HTTP_UPSTREAM_FT_ERROR) {
+         /* TODO: inform balancer instead */
+         u->peer.tries++;
++        if (u->peer.notify) {
++            u->peer.notify(&u->peer, u->peer.data, NGX_HTTP_UPSTREAM_NOTIFY_CACHED_CONNECTION_ERROR);
++        }
+     }
+ 
+     switch (ft_type) {
+diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
+index f6621af..2b5957e 100644
+--- a/src/http/ngx_http_upstream.h
++++ b/src/http/ngx_http_upstream.h
+@@ -55,6 +55,8 @@
+ #define NGX_HTTP_UPSTREAM_IGN_XA_CHARSET     0x00000100
+ #define NGX_HTTP_UPSTREAM_IGN_VARY           0x00000200
+ 
++#define NGX_HTTP_UPSTREAM_NOTIFY_CACHED_CONNECTION_ERROR 0x1
++
+ 
+ typedef struct {
+     ngx_uint_t                       status;