Description of problem:
If I try to build an image it reports Unknown Error instead of typical information like target image, status, etc.... 
output is :

ERROR:   => Unknown Error


Version-Release number of selected component (if applicable):
# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 6.2 (Santiago)
# uname -a
Linux qeblade22.rhq.lab.eng.bos.redhat.com 2.6.32-220.el6.x86_64 #1 SMP Wed Nov 9 08:03:13 EST 2011 x86_64 x86_64 x86_64 GNU/Linux

grep 'aeolus\|imagefactory-\|oz-\|iwhd'
rubygem-aeolus-cli-0.2.0-2.el6.noarch
aeolus-conductor-daemons-0.8.0-0.20111216150144gitb062bc3.el6.noarch
rubygem-arel-2.0.10-0.aeolus.el6.noarch
rubygem-rack-mount-0.7.1-3.aeolus.el6.noarch
imagefactory-jeosconf-ec2-fedora-1.0.0rc1-1.el6.noarch
rubygem-imagefactory-console-0.5.0-4.20110824113238gitd9debef.el6.noarch
oz-0.7.9-4.el6.noarch
aeolus-conductor-0.8.0-0.20111216150144gitb062bc3.el6.noarch
aeolus-all-0.8.0-0.20111216150144gitb062bc3.el6.noarch
rubygem-aeolus-image-0.2.0-1.el6.noarch
imagefactory-1.0.0rc1-1.el6.noarch
aeolus-conductor-doc-0.8.0-0.20111216150144gitb062bc3.el6.noarch
imagefactory-jeosconf-ec2-rhel-1.0.0rc1-1.el6.noarch
rubygem-ZenTest-4.3.3-2.aeolus.el6.noarch
iwhd-1.1-2.el6.x86_64
aeolus-configure-2.5.0-0.20111216121225git990f43d.el6.noarch

How reproducible:
Always

Steps to Reproduce:
1. aeolus-cleanup;aeolus-configure;
2. aeolus-cli build --target rhevm --template templates/bug761254.tdl;
3. (even with #imagefactory --debug --target rhevm --template templates/bug761254.tdl  
you get 
2011-12-19 09:20:22,380 DEBUG oz.Guest.RHEL6Guest pid(9444) Message: Launching guestfs
2011-12-19 09:20:22,589 DEBUG imgfac.builders.BaseBuilder.RHEL6_rhevm_Builder pid(9444) Message: Exception caught in ImageFactory
)

Actual results:
ERROR:   => Unknown Error

Expected results:
An image successfully built. 

Additional info:
For further info, see: 
http://hudson.rhq.lab.eng.bos.redhat.com:8080/hudson/view/DEV-CloudForms/job/ImageFactory-KocaTesting2/87/console

See the template templates/bug761254.tdl
======================================================
<template>
  <name>rhev-simple-web</name>
  <os>
    <name>RHEL-6</name>
    <version>1</version>
    <arch>x86_64</arch>
    <rootpw>redwine</rootpw>
    <install type='iso'>
      <iso>http://10.34.30.210/iso/RHEL6.1-20110510.1-Server-x86_64-DVD1.iso</iso>
    </install>
  </os>
  <description>RHEL6.1 Web for Private RHEV Clouds</description>
</template>