By default virt-manager creates qemu images in /var/lib/libvirtd/images.
For consistency koan should create them in the same directory, instead
of /opt/qemu.
The patch is available at git@github.com:ciupicri/cobbler.git branch
master-rfe497.
Link to RFE:
https://fedorahosted.org/cobbler/ticket/497
Thank you,
Cristian