restore discard body handler after ngx_http_set_writer() set it to
ngx_http_test_reading(), the bug was introduced in r3050

src/http/ngx_http.h

diff --git a/src/http/ngx_http.h b/src/http/ngx_http.h
index 5519a5b..c165491 100644
--- a/src/http/ngx_http.h
+++ b/src/http/ngx_http.h
@@ -118,6 +118,7 @@
 
 
 ngx_int_t ngx_http_discard_request_body(ngx_http_request_t *r);
+void ngx_http_discarded_request_body_handler(ngx_http_request_t *r);
 void ngx_http_block_reading(ngx_http_request_t *r);
 void ngx_http_test_reading(ngx_http_request_t *r);
 

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 485a564..bad89a4 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -2105,10 +2105,15 @@
 
     if (r->main->count != 1) {
 
-        if (r->discard_body && r->lingering_time == 0) {
-            r->lingering_time = ngx_time()
+        if (r->discard_body) {
+            r->read_event_handler = ngx_http_discarded_request_body_handler;
+            r->write_event_handler = ngx_http_request_empty_handler;
+
+            if (r->lingering_time == 0) {
+                r->lingering_time = ngx_time()
                                       + (time_t) (clcf->lingering_time / 1000);
-            ngx_add_timer(r->connection->read, clcf->lingering_timeout);
+                ngx_add_timer(r->connection->read, clcf->lingering_timeout);
+            }
         }
 
         ngx_http_close_request(r, 0);

src/http/ngx_http_request_body.c

diff --git a/src/http/ngx_http_request_body.c b/src/http/ngx_http_request_body.c
index 62c962d..be311a6 100644
--- a/src/http/ngx_http_request_body.c
+++ b/src/http/ngx_http_request_body.c
@@ -13,7 +13,6 @@
 static ngx_int_t ngx_http_do_read_client_request_body(ngx_http_request_t *r);
 static ngx_int_t ngx_http_write_request_body(ngx_http_request_t *r,
     ngx_chain_t *body);
-static void ngx_http_read_discarded_request_body_handler(ngx_http_request_t *r);
 static ngx_int_t ngx_http_read_discarded_request_body(ngx_http_request_t *r);
 static ngx_int_t ngx_http_test_expect(ngx_http_request_t *r);
 
@@ -470,7 +469,7 @@
         }
     }
 
-    r->read_event_handler = ngx_http_read_discarded_request_body_handler;
+    r->read_event_handler = ngx_http_discarded_request_body_handler;
 
     if (ngx_handle_read_event(rev, 0) != NGX_OK) {
         return NGX_HTTP_INTERNAL_SERVER_ERROR;
@@ -488,8 +487,8 @@
 }
 
 
-static void
-ngx_http_read_discarded_request_body_handler(ngx_http_request_t *r)
+void
+ngx_http_discarded_request_body_handler(ngx_http_request_t *r)
 {
     ngx_int_t                  rc;
     ngx_msec_t                 timer;