Give a better error message why NetServerSetInfo() may fail in the gui.

Guenther

source/lib/netapi/examples/netdomjoin-gui/netdomjoin-gui.c

@@ -154,7 +154,7 @@ static void callback_apply_description_change(GtkWidget *widget,
 						GTK_MESSAGE_ERROR,
 						GTK_BUTTONS_OK,
 						"Failed to change computer description: %s.",
-						libnetapi_errstr(status));
+						libnetapi_get_error_string(state->ctx, status));
 		g_signal_connect_swapped(dialog, "response",
 					 G_CALLBACK(gtk_widget_destroy),
 					 dialog);

source/lib/netapi/serverinfo.c

@@ -185,6 +185,9 @@ static WERROR NetServerSetInfoLocal_1005(struct libnetapi_ctx *ctx,
 	}
 
 	if (!lp_config_backend_is_registry()) {
+		libnetapi_set_error_string(ctx,
+			"Configuration manipulation requested but not "
+			"supported by backend");
 		return WERR_NOT_SUPPORTED;
 	}