KVM storage hot-plug is unable to use the device nodes of previously detached disks.

Description of problem:

Even though hot-unplug removes the disk from the VM, next hot-plug is not able to utilize the same device node of the previously detached disk, but it hot-plugs the disk to a new device node.

Environment:
host:
RHEL 5.5
libvirt-0.8.2-15.el5_6.1.x86_64
kernel-2.6.18-238.1.1.el5

Guest:
RHEL 5.6
kernel-2.6.18-238.el5

How reproducible:

1. Load following modules to VM kernel

# modprobe acpiphp
# modprobe virtio_blk

2. Attach a virtio disk to the VM either from virt-manager or by using following command

#  virsh attach-disk --driver file RHEL5.6_64  /vm/KVM/test1.img vdb
Disk attached successfully

3. Detach this disk from the VM

# virsh detach-disk RHEL5.6_64  vdb
Disk detached successfully

4. Now try to attach the disk again as "vdb"
  
Actual results:

Newly attached target "vdb" appeares as "/dev/vde" inside VM.

Expected results:

It should present as "/dev/vdb" itself.

Additional info:

Even though VM identifies the disk as "/dev/vde", to detach the disk again we have to specify the target as "vdb"

# virsh detach-disk RHEL5.6_64  vdb
Disk detached successfully

this would detach /dev/vde from the VM.