Description of problem:
Win7 guest cannot be saved on KVM hypervisor

Version-Release number of selected component (if applicable):
kernel-2.6.18-262.el5
virt-manager-0.6.1-14.el5
libvirt-0.8.2-20.el5
kvm-qemu-img-83-232.el5

How reproducible:
Always

Steps to Reproduce:
1. Install win7 guest on real disk, here is /dev/sda3
2. Open the win7 detail window, on the menu list, select "Virtual Machine" and click "Save"
3. Input the name and click "Save"
  
Actual results:
Error saving domain: operation failed: migration to 'exec:cat | { dd bs=4096 seek=1 if=/dev/null && dd bs=1048576; } 1<>/var/lib/libvirt/win7' failed: migration failed

Expected results:
the guest can be saved successfully.

Additional info:

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 435, in _save_callback
    vm.save(file_to_save)
  File "/usr/share/virt-manager/virtManager/domain.py", line 597, in save
    vm.save(filename)
  File "/usr/lib64/python2.4/site-packages/libvirt.py", line 608, in save
    if ret == -1: raise libvirtError ('virDomainSave() failed', dom=self)
libvirtError: operation failed: migration to 'exec:cat | { dd bs=4096 seek=1 if=/dev/null && dd bs=1048576; } 1<>/var/lib/libvirt/win7' failed: migration failed