This fixes the error message triggered by the following script:

    cat > /tmp/blkdebug.cfg <<EOF
    [inject-error]
    event = "cluster_free"
    errno = "28"
    immediately = "off"
    EOF

    $qemu_img create -f qcow2 test.qcow2 10G
    $qemu_img snapshot -c snap test.qcow2
    $qemu_img snapshot -d snap blkdebug:/tmp/blkdebug.cfg:test.qcow2
Signed-off-by: NKevin Wolf <kwolf@redhat.com>