reset ready flag if no data is available,
this fixes endless loop at least in lingering close

src/os/unix/ngx_recv.c

diff --git a/src/os/unix/ngx_recv.c b/src/os/unix/ngx_recv.c
index 6361b3c..f4d6a2b 100644
--- a/src/os/unix/ngx_recv.c
+++ b/src/os/unix/ngx_recv.c
@@ -41,6 +41,7 @@
                 return 0;
 
             } else {
+                rev->ready = 0;
                 return NGX_AGAIN;
             }
         }