ampersand in MUC topic / title breaks tab title
Bug description
An ampersand in the topic / title (not sure where the difference is) cannot be display by gajim and leaves an empty tab / chat window title. The corresponding error message from the log is:
/usr/share/gajim/src/message_window.py:657: GtkWarning: Failed to set text from markup due to error parsing markup: Fehler in Zeile 1: Entität endete nicht mit einem Semikolon; wahrscheinlich haben Sie ein &-Zeichen benutzt, ohne eine Entität beginnen zu wollen - umschreiben Sie das »&« als &
nick_label.set_markup(tab_label_str)
Parts of this is in German. What is basically says is: "You did not escape the &, please write & instead of &" If I change the topic with gajim and replace the "&" with the word "and" this bug still persists.
Steps to reproduce
Create a new MUC with Conversations and a topic /title (Conversations does not distinguish) that contains a "&". Open gajim with the same account and join the MUC.
Software versions
OS version: Fedora 24, Gnome 3.20
GTK version: 3.20 (I guess)
PyGTK version: I don't know.