Test this issue with:
VMware ESXi Version 5.0.0 Build 469512
libvirt-python-0.9.4-23.el6_2.2.x86_64
libvirt-client-0.9.4-23.el6_2.2.x86_64
libvirt-0.9.4-23.el6_2.2.x86_64

Steps:

1.# virsh -c esx://10.66.6.211/?no_verify=1
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # list --all
 Id Name                 State
----------------------------------
  - esx5.0-rhel5.7-i386  shut off
  - esx5.0-rhel5.7-x86_64 shut off
  - esx5.0-rhel6.2-i386  shut off
2.Start a guest
# virsh -c esx://10.66.6.211/?no_verify=1 start esx5.0-rhel6.2-i386
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
Domain esx5.0-rhel6.2-i386 started

# virsh -c esx://10.66.6.211/?no_verify=1 list 
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
 Id Name                 State
----------------------------------
  5 esx5.0-rhel6.2-i386  running

3.Dumpxml of guest.
# virsh -c esx://10.66.6.211/?no_verify=1 dumpxml esx5.0-rhel6.2-i386
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
<domain type='vmware' id='5'>
  <name>esx5.0-rhel6.2-i386</name>
  <uuid>564d3e09-815e-4a09-33e4-27a1ed42adb2</uuid>
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='i686'>hvm</type>
  </os>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <disk type='file' device='disk'>
      <source file='[datastore1] esx5.0-rhel6.2-i386/esx5.0-rhel6.2-i386-000001.vmdk'/>
      <target dev='sda' bus='scsi'/>
...

4.Define a guest.
# virsh -c esx://10.66.6.211/?no_verify=1 define esxi5.xml
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
Domain test5.0 defined from esxi5.xml

# virsh -c esx://10.66.6.211/?no_verify=1 list --all
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
 Id Name                 State
----------------------------------
  5 esx5.0-rhel6.2-i386  running
  - test5.0              shut off

5.Undefine a guest.
# virsh -c esx://10.66.6.211/?no_verify=1 undefine test5.0
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
Domain test5.0 has been undefined

6.Destroy a guest.
virsh -c esx://10.66.6.211/?no_verify=1 destroy esx5.0-rhel6.2-i386
Enter username for 10.66.6.211 [root]: 
Enter root's password for 10.66.6.211: 
Domain esx5.0-rhel6.2-i386 destroyed

It works well for me.

Verified the bug with:
VMware ESXi Version 5.0.0 Build 469512
libvirt-0.9.4-23.el6_2.4.x86_64
libvirt-client-0.9.4-23.el6_2.4.x86_64
libvirt-python-0.9.4-23.el6_2.4.x86_64

The steps are the same with comment 6.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2012-0013.html

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