Use proper pngtest.png reference image on aarch64

libpng.spec

@@ -2,12 +2,13 @@ Summary:       A library of functions for manipulating PNG image format files
 Name:          libpng
 Epoch:         2
 Version:       1.6.37
-Release:       7%{?dist}
+Release:       8%{?dist}
 License:       zlib
 URL:           http://www.libpng.org/pub/png/
 
 Source0:       https://github.com/glennrp/%{name}/archive/v%{version}/%{name}-%{version}.tar.gz
 Source1:       pngusr.dfa
+Source2:       pngtest-aarch64.png
 Patch0:        libpng-multilib.patch
 Patch1:        libpng-fix-arm-neon.patch
 
@@ -60,6 +61,12 @@ The libpng-tools package contains tools used by the authors of libpng.
 # Provide pngusr.dfa for build.
 cp -p %{SOURCE1} .
 
+%ifarch aarch64
+# zlib on aarch64 produces output different from other arches:
+# https://bugzilla.redhat.com/show_bug.cgi?id=1665221
+cp -p %{SOURCE2} pngtest.png
+%endif
+
 %patch0 -p1
 %patch1 -p1 -b .arm
 
@@ -103,6 +110,9 @@ make check
 %{_bindir}/pngfix
 
 %changelog
+* Fri Feb 05 2021 Nikola Forró <nforro@redhat.com> - 2:1.6.37-8
+- Use proper pngtest.png reference image on aarch64
+
 * Tue Jan 26 2021 Fedora Release Engineering <releng@fedoraproject.org> - 2:1.6.37-7
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass_Rebuild