[gnome-music/wip/mschraal/template-trackwidget] disclistboxwidget: Fix show_disc_label

[Marinus Schraal <mschraal src gnome org>]

commit 2f42d70b9fc870ffe91644f46274e656ee7730cf
Author: Marinus Schraal <mschraal gnome org>
Date:   Mon Apr 23 01:21:09 2018 +0200

    disclistboxwidget: Fix show_disc_label
    
    This never worked as intended, just by chance it did and so never got
    noticed.

 gnomemusic/widgets/disclistboxwidget.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/gnomemusic/widgets/disclistboxwidget.py b/gnomemusic/widgets/disclistboxwidget.py
index faf189a9..7b3803f8 100644
--- a/gnomemusic/widgets/disclistboxwidget.py
+++ b/gnomemusic/widgets/disclistboxwidget.py
@@ -144,8 +144,7 @@ class DiscBox(Gtk.Box):
 
         :param bool show_header: Display the disc number label
         """
-        self._label.set_visible(False)
-        self._label.hide()
+        self._label.set_visible(show_header)
 
     @log
     def show_duration(self, show_duration):