block favicon can be completely be overridden

basetheme_bootstrap/templates/basetheme_bootstrap/basePasteur.html

@@ -8,7 +8,7 @@
     <title>{% block title %}{% endblock %}</title>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
-    <link rel="icon" href="{% block favicon %}/static/img/favicon.png{% endblock %}">
+    {% block favicon %}<link rel="icon" href="/static/img/favicon.png">{% endblock %}
 
     <!-- Bootstrap core CSS -->
     <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"