fix post_action for disconnected client

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 8a86f2e..2c1ac95 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -2247,6 +2247,8 @@
     r->header_only = 1;
     r->post_action = 1;
 
+    r->read_event_handler = ngx_http_block_read;
+
     ngx_http_internal_redirect(r, &clcf->post_action, NULL);
 
     return NGX_OK;