backoffice: reset breadcrumb to have its first element be the backoffice

wcs/backoffice/root.py

@@ -116,6 +116,7 @@ class RootDirectory(BackofficeRootDirectory):
         return False
 
     def _q_access(self):
+        get_response().breadcrumb = [] # reinit, root the breadcrumb in the backoffice
         get_response().breadcrumb.append( ('backoffice/', _('Back Office')) )
         req = get_request()