Description of problem:
when a vm is running,type stop in monitor,
after vm stopped,migrate to file twice ,file size differs

Version-Release number of selected component (if applicable):

qemu-kvm-0.12.1.2-2.158.el6.x86_64
How reproducible:
100%

Steps to Reproduce:
1.boot a guest
qemu-kvm -name 'rhel47-32' -monitor stdio -E,path=/tmp/serial-20110420-134929-ocyE,server,nowait -device isa-serial,chardev=E -drive file='2.qcow2',werror=stop,rerror=stop,index=0,if=ide,cache=unsafe -device rtl8139,netdev=idvjxRgD,mac=9a:fe:9d:9b:1e:a4,id=ndev00idvjxRgD,bus=pci.0,addr=0x3 -netdev tap,id=idvjxRgD,ifname='t0',script='/.',downscript='no' -m 4096 -smp 4,cores=2,threads=1,sockets=2 -cpu cpu64-rhel6,+sse2,+x2apic -vnc :0 -rtc base=utc,clock=host,driftfix=none -M rhel6.1.0 -boot order=cdn,once=c,menu=off   -usbdevice tablet -no-kvm-pit-reinjection -enable-kvm  


2. after guest fully booted,type "stop" in monitor
3. exec     "migrate -d "exec:gzip -c > /tmp/mig1.gz"
after finish migration,do 
  "migrate -d "exec:gzip -c > /tmp/mig2.gz"
Actual results:
/tmp/mig1    /tmp/mig2    size differs

ll /tmp/mig*

-rw-r--r--. 1 root root 2503468 Apr 21 12:45 /tmp/mig1.gz
-rw-r--r--. 1 root root 2503467 Apr 21 12:45 /tmp/mig2.gz

[root@rhel6xwei tmp]# md5sum  mig*
c268c82cce9b83f2a5b7f7b339ad39f5  mig1.gz
22705f6213f6de1b25cd091869e11641  mig2.gz

Expected results:
mig1.gz mig2.gz  size the same,md5sum the same.

Additional info:
host info :kernel-2.6.32-130.el6.x86_64
processor       : 3
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Core(TM)2 Quad CPU    Q9400  @ 2.66GHz
stepping        : 10
cpu MHz         : 2660.161
cache size      : 3072 KB

guest info : OS rhel4.9-32 / Win2008-64