I tested on a 32-bits system equiped with a Geforce 8800 GTX and on a 64-bits system with an I5 processor graphics. The same bug on the two different systems.
I knew it that the patch would cause some problems. I didn't apply it and unfortunately I never had the time to properly check it.
What it did wrong is simple: Instead of the scaling factor coming from the map data it used the composite scaling factor of both map data and texture definition which effectively applied the texture based part twice.
This is why I am very careful with user-submitted patches that change sensitive code. This should never have been added without a full review of the effects.