graphic: 0.850
device: 0.762
instruction: 0.747
semantic: 0.729
network: 0.714
mistranslation: 0.471
other: 0.457
socket: 0.444
boot: 0.372
vnc: 0.259
KVM: 0.169
assembly: 0.144

qemu-img create  will silently overwrite existing image
Description of problem:
If file exists, it is silently overwritten, causing loss of data. oups.