There were two issues here actually: * The hack to allow running Blender directly from the source directory would just check for a 'release' directory, without actually ensuring it is release dir from blender source tree, and not some other random folder. * GHOST_getSystemDir returns nothing for portable installations, now we'll then check directly in the blender binary dir in that case. This fix is more critical in 2.8 branch, where that system path is used to retrieve new '3D' icons...