TS-4522: check EPIPE instead r==0

man 2 write, Return value, On Success, the number of bytes written is returned (zero indicates nothing was written). On error, -1 is returned, and errno is set appropriately.

Author: oknet

iocore/net/UnixNetVConnection.cc

@@ -535,7 +535,7 @@ write_to_net_io(NetHandler *nh, UnixNetVConnection *vc, EThread *thread)
       }
       return;
     }
-    if (!r || r == -ECONNRESET) {
+    if (r == -EPIPE || r == -ECONNRESET) {
       vc->write.triggered = 0;
       write_signal_done(VC_EVENT_EOS, nh, vc);
       return;