qemu segfaults when security_model=none using virtio-9p-pci driver

qemu version: 0.13
commit-id: 6ed912999d6ef636a5be5ccb266d7d3c0f0310b4

example invocation:
$ qemu -virtfs local,path=/tmp,security_model=none,mount_tag=mmm r.img
one of the following must be specified as thesecurity option:
         security_model=passthrough 
         security_model=mapped
Segmentation fault

Patch is attached. Also attached is a patch that addes the space between 'the' and 'security' in 'thesecurity'.

Does not affect trunk.