Why does "rhevm-upgrade" fail from with yum error?

Issue

• Why does rhevm-upgrade fail with yum error?
• Below logs seen in /var/log/ovirt-engine/ovirt-engine-upgrade file, where the failure is observed:

2013-05-08 12:52:23::DEBUG::common_utils::339::root:: Executing command --> '/usr/bin/yum update -q -y rhevm rhevm-backend rhevm-config rhevm-dbscripts rhevm-genericapi rhevm-notification-service rhevm-restapi rhevm-setup rhevm-tools-com
mon rhevm-userportal rhevm-webadmin-portal rhevm-image-uploader rhevm-iso-uploader rhevm-log-collector vdsm-bootstrap'
2013-05-08 12:52:31::DEBUG::common_utils::377::root:: output =  You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest

2013-05-08 12:52:31::DEBUG::common_utils::378::root:: stderr = Error: Package: rhevm-3.1.0-53.el6ev.noarch (rhel-x86_64-server-6-rhevm-3.1)
           Requires: virtio-win >= 1.6.3-3
           Installed: virtio-win-1.5.3-1.el6_3.noarch (@rhel-x86_64-server-supplementary-6)
               virtio-win = 1.5.3-1.el6_3
.
.
2013-05-08 12:52:31::DEBUG::common_utils::378::root:: stderr = 
2013-05-08 12:52:31::DEBUG::common_utils::379::root:: retcode = 0
2013-05-08 12:52:31::DEBUG::rhevm-upgrade::356::root:: Yum lock completed successfully
2013-05-08 12:52:31::ERROR::rhevm-upgrade::1443::root:: Traceback (most recent call last):
  File "/usr/bin/rhevm-upgrade", line 1411, in main
    runFunc(upgradeFunc, MSG_INFO_YUM_UPDATE)
  File "/usr/bin/rhevm-upgrade", line 692, in runFunc
    func()
  File "/usr/bin/rhevm-upgrade", line 383, in update
    output, rc = utils.execCmd(cmdList=cmd, failOnError=True, msg=MSG_ERROR_YUM_UPDATE)
  File "/usr/share/ovirt-engine/scripts/common_utils.py", line 382, in execCmd
    raise Exception(msg)
Exception: Error: Yum update failed

2013-05-08 12:52:31::ERROR::rhevm-upgrade::1444::root:: Rolling back update
2013-05-08 12:52:31::DEBUG::rhevm-upgrade::703::root:: Verifing update is related to db
2013-05-08 12:52:31::DEBUG::rhevm-upgrade::713::root:: isUpdateRelatedToDb value is True
2013-05-08 12:52:31::DEBUG::rhevm-upgrade::574::root:: DB Restore started
2013-05-08 12:52:31::DEBUG::common_utils::339::root:: Executing command --> '/usr/bin/dropdb -U engine -h localhost -p 5432 engine_2013_05_08_12_49_07'
2013-05-08 12:52:39::DEBUG::common_utils::377::root:: output = 
2013-05-08 12:52:39::DEBUG::common_utils::378::root:: stderr = 
2013-05-08 12:52:39::DEBUG::common_utils::379::root:: retcode = 0
2013-05-08 12:52:39::DEBUG::common_utils::339::root:: Executing command --> '/usr/bin/psql -U engine -h localhost -p 5432 -d template1 -f /var/lib/ovirt-engine/backups/ovirt-engine_db_backup_2013_05_08_12_49_07.sql'
2013-05-08 12:53:07::DEBUG::common_utils::377::root:: output = SET
.
.
2013-05-08 12:53:10::ERROR::rhevm-upgrade::1521::root:: Traceback (most recent call last):
  File "/usr/bin/rhevm-upgrade", line 1514, in <module>
    main(options)
  File "/usr/bin/rhevm-upgrade", line 1457, in main
    runFunc([rhyum.rollback], MSG_INFO_YUM_ROLLBACK)
  File "/usr/bin/rhevm-upgrade", line 692, in runFunc
    func()
  File "/usr/bin/rhevm-upgrade", line 480, in rollback
    raise Exception(MSG_ERROR_YUM_TID)
Exception: Error: Yum transaction mismatch

• yum install rhevm fails with below error:

--> Processing Dependency: virtio-win >= 1.6.6-1 for package: rhevm-3.3.3-0.52.el6ev.noarch
--> Finished Dependency Resolution
Error: Package: rhevm-3.3.3-0.52.el6ev.noarch (rhel-6-server-rhevm-3.3-rpms)
           Requires: virtio-win >= 1.6.6-1
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest