Code review comment for lp:~widelands-dev/widelands/richtext_testing

One more test please. I found a machine were the tests did not pass and I copied their wrong.png to correct.png and the tests still pass on my machine - weirdly enough. This points me to some weirdness in how PNGs are saved or loaded.

My guess is that the tests now pass on your machines too. If that is the case, I'll call this done.