Description of problem:
Ejecting a busy floppy from guest causes I/O error

Version-Release number of selected component (if applicable):
- libvirt-0.8.7-8.el6.x86_64
- kernel-2.6.32-114.0.1.el6.x86_64
- qemu-kvm-0.12.1.2-2.144.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. Add a floppy to guest xml 
    </disk>
      <disk type='block' device='floppy'>
      <driver name='qemu' type='raw'/>
      <source dev='/var/lib/libvirt/images/floppy1.img'/>
      <target dev='fda' bus='fdc'/>
    </disk>
2. Define and start the guest
3. In guest, 
# modprobe floppy
# mount /dev/fd0 /mnt
4.Prepare a eject.xml
# cat eject.xml 
   <disk type='block' device='floppy'>
     <target dev='fda' bus='fdc'/>
   </disk>
5. # virsh update-device rhel61_i386_11 eject.xml 
Device updated successfully

Actual results:
5. Could eject a busy floppy in guest without --force, and seconds later, could see I/O error in guest (please see the attachment)

Expected results:
6. Should cannot eject a busy floppy in guest without --force, surely should not cause I/O error in guest

Additional info: