Merge pull request #275 from luke-jr/qemu_backing_fmt

make-clean-vm: Specify backing_fmt to qemu-img explicitly

Author: devrandom

libexec/make-clean-vm

@@ -58,7 +58,7 @@ OUT=target-$SUITE-$ARCH
 
 case $VMSW in
   KVM)
-    qemu-img create -f qcow2 -o backing_file="$BASE.qcow2" "$OUT.qcow2"
+    qemu-img create -f qcow2 -o backing_fmt=qcow2,backing_file="$BASE.qcow2" "$OUT.qcow2"
     ;;
   LXC)
     cp -a --sparse=always $BASE $OUT