Why "yum update" fails with "Transaction Check Error" on the rhevm system ?

Issue

• yum update fails with "Transaction Check Error" on the rhevm system:

======================================================================================================
 Package                Arch      Version                         Repository                     Size
======================================================================================================
Installing:
 kernel                 x86_64    2.6.32-358.14.1.el6             rhel-x86_64-server-6           26 M
 python-imgcreate       x86_64    1:13.4.3-1.el6                  rhel-x86_64-server-6-rhevh     87 k
     replacing  rhev-hypervisor6-tools.noarch 6.3-20121012.0.el6_3
Updating:
 bash                   x86_64    4.1.2-15.el6_4                  rhel-x86_64-server-6          904 k
 bind-libs              x86_64    32:9.8.2-0.17.rc1.el6_4.5       rhel-x86_64-server-6          878 k
 bind-utils             x86_64    32:9.8.2-0.17.rc1.el6_4.5       rhel-x86_64-server-6          182 k
 crash-gcore-command    x86_64    1.0-4.el6_4                     rhel-x86_64-server-6           37 k
 irqbalance             x86_64    2:1.0.4-4.el6_4                 rhel-x86_64-server-6           37 k
 kernel-firmware        noarch    2.6.32-358.14.1.el6             rhel-x86_64-server-6           11 M
 krb5-libs              x86_64    1.10.3-10.el6_4.4               rhel-x86_64-server-6          760 k
 krb5-workstation       x86_64    1.10.3-10.el6_4.4               rhel-x86_64-server-6          805 k
 libtevent              x86_64    0.9.18-1.el6_4                  rhel-x86_64-server-6           26 k
 net-snmp               x86_64    1:5.5-44.el6_4.3                rhel-x86_64-server-6          303 k
 net-snmp-libs          x86_64    1:5.5-44.el6_4.3                rhel-x86_64-server-6          1.5 M
 scl-utils              x86_64    20120927-2.el6_4.6              rhel-x86_64-server-6           15 k
 xorg-x11-drv-mga       x86_64    1.6.1-8.el6_4                   rhel-x86_64-server-6           72 k

Transaction Summary
======================================================================================================
Install       2 Package(s)
Upgrade      13 Package(s)

Total download size: 43 M
Is this ok [y/N]: y
Downloading Packages:
(1/15): bash-4.1.2-15.el6_4.x86_64.rpm                                         | 904 kB     00:04     
(2/15): bind-libs-9.8.2-0.17.rc1.el6_4.5.x86_64.rpm                            | 878 kB     00:05     
(3/15): bind-utils-9.8.2-0.17.rc1.el6_4.5.x86_64.rpm                           | 182 kB     00:01     
(4/15): crash-gcore-command-1.0-4.el6_4.x86_64.rpm                             |  37 kB     00:00     
(5/15): irqbalance-1.0.4-4.el6_4.x86_64.rpm                                    |  37 kB     00:00     
(6/15): kernel-2.6.32-358.14.1.el6.x86_64.rpm                                  |  26 MB     02:40     
(7/15): kernel-firmware-2.6.32-358.14.1.el6.noarch.rpm                         |  11 MB     00:27     
(8/15): krb5-libs-1.10.3-10.el6_4.4.x86_64.rpm                                 | 760 kB     00:03     
(9/15): krb5-workstation-1.10.3-10.el6_4.4.x86_64.rpm                          | 805 kB     00:03     
(10/15): libtevent-0.9.18-1.el6_4.x86_64.rpm                                   |  26 kB     00:00     
(11/15): net-snmp-5.5-44.el6_4.3.x86_64.rpm                                    | 303 kB     00:02     
(12/15): net-snmp-libs-5.5-44.el6_4.3.x86_64.rpm                               | 1.5 MB     00:04     
(13/15): python-imgcreate-13.4.3-1.el6.x86_64.rpm                              |  87 kB     00:00     
(14/15): scl-utils-20120927-2.el6_4.6.x86_64.rpm                               |  15 kB     00:00     
(15/15): xorg-x11-drv-mga-1.6.1-8.el6_4.x86_64.rpm                             |  72 kB     00:00     
----------------------------------------------------------------------------------------------------------------
Total                                                                 157 kB/s |  43 MB     04:37     
Running rpm_check_debug
Running Transaction Test


Transaction Check Error:
  package python-imgcreate-1:13.4.3-1.el6.x86_64 is already installed

Error Summary
-------------