Hi, when trying to troubleshoot bug #41467 i tried to add ksvg to DO_NOT_COMPILE... use scanner || DO_NOT_COMPILE="$DO_NOT_COMPILE kooka libkscan ksvg" that didn't work - ie. the ebuild still wanted to compile ksvg. i found the reason it didn't compile kooka and libkscan was due to missing deps (libsane or the like) when i changed it to: use scanner || export DO_NOT_COMPILE="$DO_NOT_COMPILE kooka libkscan ksvg" kvsg was not compiled...
It's possible that during your debugging, portage cached a value of that variable that was later used instead of the default, but a fresh install should pick it up just fine.
should be better now.