Bug#1093335: gtk4: FTBFS and autopkgtest failure: test regressions with libpng 1.6.45

[Simon McVittie]

On Sat, 18 Jan 2025 at 11:39:41 +0000, Simon McVittie wrote:
> >  65/693 gtk:gsk+gsk-nodeparser / parser empty-texture.node                           FAIL             0.03s   exit status 1
> >  66/693 gtk:gsk+gsk-nodeparser / parser empty-texture-scale.node                     FAIL             0.03s   exit status 1
> >  94/693 gtk:gsk+gsk-nodeparser / parser texture-fail.node                            FAIL             0.03s   exit status 1
> >  95/693 gtk:gsk+gsk-nodeparser / parser texture-names.node                           FAIL             0.02s   exit status 1
> >  96/693 gtk:gsk+gsk-nodeparser / parser texture-scale-filters.node                   FAIL             0.03s   exit status 1
> >  97/693 gtk:gsk+gsk-nodeparser / parser texture-scale-unknown-filter.node            FAIL             0.03s   exit status 1
> 
> These are "reftests" which draw the same scene in two different ways,
> and assert that the node tree in GSK's scene graph is equivalent. With
> libpng 1.6.44, they pass.

Sorry, pressed send too soon. What I meant to say for the rest of that
paragraph is:

If I'm understanding correctly, with libpng 1.6.45, the small texture
that is involved in these tests (which is serialized as a data: URI
containing a base64-encoded PNG) is different in the serializations of
the two scene graphs - probably a colour space difference, the same as
the other failing test? - and as a result the test fails.

    smcv