This message occours whenever Insync is installed or upgraded. It is not only written to the console, but also appears as a graphical yes/no dialog. It would be better if Insync would stay inside the console. Commands like
dnf update should not spawn unexpected message boxes.
Upgrading : insync-126.96.36.199059-fc21.x86_64 25/58 which: no xmessage in (/sbin:/bin:/usr/sbin:/usr/bin:/usr/X11R6/bin) Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged. OK Insync installation has finished. You may now start it.