PNG files can capture build time with the tIME chunk and custom keywords.

Known affected packages

Detection

Example debbindiff output

Workaround

strip-nondeterminism since version 0.006 is stripping timestamps from PNG files.

Solution

If the PNG is being generated by ?ImageMagick, some options can be passed to convert to inhibit inclusion of the timestamps. Please note that the options have to be passed just before the output filename and composite only supports the time chunk removal, for example:

convert -strip -scale 32x32 input.png output.png # or
convert -scale 32x32 input.png +set date:create +set date:modify -define png:exclude-chunk=time output.png
composite -compose CopyOpacity mask.png input.png -define png:exclude-chunk=time output.png

Example patch