Make sure to use the right exception when the distro can't be found.
Make sure to use the right exception when the distro can't be found.

Signed-off-by: Chris Lalancette <60b62644009db6b194cc0445b64e9b27bb26433a@redhat.com>

mgagne/oz,nullr0ute/oz,cernops/oz,ndonegan/oz,moofrank/oz,NeilBryant/oz,clalancette/oz,nullr0ute/oz,NeilBryant/oz,clalancette/oz,moofrank/oz,imcleod/oz,mgagne/oz,cernops/oz,ndonegan/oz,imcleod/oz