register checks for dcl->ds being NULL, to avoid registering
the same dcl twice.

Therefore dcl->ds must be cleared on unregister, otherwise
un-registering and re-registering doesn't work.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1510809
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 ui/console.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ui/console.c b/ui/console.c
index eca854cbd5..c4c95abed7 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1471,6 +1471,7 @@ void unregister_displaychangelistener(DisplayChangeListener *dcl)
         dcl->con->dcls--;
     }
     QLIST_REMOVE(dcl, next);
+    dcl->ds = NULL;
     gui_setup_refresh(ds);
 }
 
-- 
2.9.3