Version 1.8 of potrace has been released. A simple copy of the 1.7 ebuild worked for me (on ~x86). That said, --enable-a4 should not be passed unconditionally, as it is in the 1.7 ebuild. And those who do want it probably also want --enable-metric. Perhaps add a local use flag of metric and use_enable both when it is set?
*** Bug 200169 has been marked as a duplicate of this bug. ***
@fonts - do you want this since you already maintain media-gfx/potracegui?
i'll bump it but i think it should be graphics. fixed, thanks. ;)