使用 ISO 创建 qemu VM 时，virt-manager 错误“format=dir: 'dir' invalid format”

Question

这是 Fedora 20 上的 virt-manager 1.0.1。服务器在 Arch Linux 上有 libvirt 1.2.13-1、qemu 2.2.1-2。

去文件 -> 新建虚拟机。选择使用 ISO 映像从安装然后浏览它。完成向导会出现这个相当丑陋的错误：

Unable to complete install: 'internal error: process exited while connecting to monitor: 2015-04-28T07:24:09.432905Z qemu-system-x86_64: -drive file=/var/lib/libvirt/images/Intel_Install/openSUSE/openSUSE-13.2-DVD-x86_64.iso,if=none,id=drive-ide0-0-0,readonly=on,format=dir: 'dir' invalid format
'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 91, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/create.py", line 1787, in do_install
    guest.start_install(meter=meter)
  File "/usr/share/virt-manager/virtinst/guest.py", line 403, in start_install
    noboot)
  File "/usr/share/virt-manager/virtinst/guest.py", line 467, in _create_guest
    dom = self.conn.createLinux(start_xml or final_xml, 0)
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 2897, in createLinux
    if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self)
libvirtError: internal error: process exited while connecting to monitor: 2015-04-28T07:24:09.432905Z qemu-system-x86_64: -drive file=/var/lib/libvirt/images/Intel_Install/openSUSE/openSUSE-13.2-DVD-x86_64.iso,if=none,id=drive-ide0-0-0,readonly=on,format=dir: 'dir' invalid format

我尝试在 virt-manager 中编辑虚拟机（安装前自定义配置) 将格式更改为生的但仍然看到相同的“format=dir: 'dir' 格式无效”错误。

如何修复或绕过此错误来构建虚拟机？以前的版本是没问题的。