[widelands] Add comment with upstream bug url for libpng-1.5 compat

[Hans de Goede]

commit 3e661b149f63adf7ef07671288589bdea79fe76e
Author: Hans de Goede <hdegoede at redhat.com>
Date:   Tue Dec 6 15:21:55 2011 +0100

    Add comment with upstream bug url for libpng-1.5 compat

 widelands.spec |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/widelands.spec b/widelands.spec
index 5382773..ca3795f 100644
--- a/widelands.spec
+++ b/widelands.spec
@@ -9,6 +9,7 @@ License:        GPLv2+
 URL:            http://www.widelands.org
 Source0:        http://launchpad.net/widelands/%{build_id}/%{build_id}/+download/widelands-%{build_id}-src.tar.bz2
 Patch0:         widelands-build16-src-crash-on-messagebox.patch
+# Reported upstream: https://bugs.launchpad.net/widelands/+bug/900767
 Patch1:         widelands-build16-src-libpng15.patch
 
 BuildRequires: SDL_mixer-devel SDL_image-devel SDL_net-devel SDL_ttf-devel