Fix propagation of RPC errors from streams

If a streams error is raised, virNetClientIOEventLoop
returns 0, but an error is set. Check for this and
propagate it if present

* src/rpc/virnetclient.c: Propagate streams error

src/rpc/virnetclient.c

@@ -1090,10 +1090,15 @@ static int virNetClientIO(virNetClientPtr client,
      */
     virNetSocketUpdateIOCallback(client->sock, 0);
 
+    virResetLastError();
     rv = virNetClientIOEventLoop(client, thiscall);
 
     virNetSocketUpdateIOCallback(client->sock, VIR_EVENT_HANDLE_READABLE);
 
+    if (rv == 0 &&
+        virGetLastError())
+        rv = -1;
+
 cleanup:
     VIR_DEBUG("All done with our call %p %p %d", client->waitDispatch, thiscall, rv);
     return rv;