CppunitTest_sw_htmlexport failing due to zlib variation?

[Stephan Bergmann]

On 25/08/2020 11:07, Stephan Bergmann wrote:
> At least when building recent master on recent Fedora rawhide aarch64 
> with (among others) --with-system-zlib, CppunitTest_sw_htmlexport fails 
> with
[...]
> The base64-encoded payload apparently is a PNG image.  And from what 
> little I know about PNG, it looks plausible to me that there can be 
> different (compressed) PNG content that decompress to identical raw 
> data, and that the LibreOffice code would be allowed to generate 
> differing (compressed) PNG content for the above data:image/png URL 
> payload.

What supports the theory that "the LibreOffice code would be allowed to 
generate differing (compressed) PNG content" is the Fedora zlib commit 
<https://src.fedoraproject.org/rpms/zlib/c/25e9802713484882c27c1f979a6610a42414ee13> 
"aarch64 optimizations", adding lots of code that presumably is only 
relevant for aarch64 and presumably changes details of the compression 
algorithm.