[tex-live] tl2018: problems with including a (very specific) PNG file

[Karl Berry]

    The attached files build œôòüfineœôòý with tl2009, but produce a very bad
    result with tl2018.

I don't get any difference in the output between 2009 and today (on
x86-linux), but anyway, whatever is going on I believe is in the LaTeX
drivers rather than the pdftex binary, because it worked normally with
plain pdftex. So I posted here:
https://github.com/latex3/graphics-def/issues/18

I surmise a workaround could be to open/save the png, or run through
pngtopnm|pnmtopng, or whatever, since clearly that particular png is
indeed "unusual". --best, karl.