If the comment is correct, this code is not needed anymore

This was introduced at 3da25187.

src/frontends/qt/GuiIdListModel.cpp

@@ -66,10 +66,6 @@ bool GuiIdListModel::setData(QModelIndex const & index,
 	if (role == Qt::DecorationRole)
 		// nothing to do
 		return true;
-	if (role == Qt::UserRole - 1)
-		// This role is set by Qt <= 5.5 if setEditable()
-		// of the item is false
-		return true;
 	// If we assert here, it's because we're trying to set an
 	// unrecognized role.
 	LATTEST(false);