Description of problem:
when updating a host (yum update), there is an issue when 2 packages of redhat-release are installed (before yum cleans up the old package), vdsmd is restarted and fails to start.

Thread-92::DEBUG::2011-10-09 11:47:30,149::clientIF::54::vds::(wrapper) [10.35.64.13]::call getVdsCapabilities with () {}
Thread-92::ERROR::2011-10-09 11:47:30,191::caps::137::root::(osversion) failed to find version/release
Traceback (most recent call last):
  File "/usr/share/vdsm/caps.py", line 133, in osversion
    version, release = out.split()
ValueError: too many values to unpack
Thread-92::ERROR::2011-10-09 11:47:30,192::clientIF::68::vds::(wrapper) Traceback (most recent call last):
  File "/usr/share/vdsm/clientIF.py", line 58, in wrapper
    res = f(*args, **kwargs)
  File "/usr/share/vdsm/clientIF.py", line 712, in getVdsCapabilities
    c = caps.get()
  File "/usr/share/vdsm/caps.py", line 173, in get
    caps['operatingSystem'] = osversion()
  File "/usr/share/vdsm/caps.py", line 139, in osversion
    __osversion = dict(release=release, version=version, name=osname)
UnboundLocalError: local variable 'release' referenced before assignment



            p = subprocess.Popen([constants.EXT_RPM, '-qf', '--qf',
                '%{VERSION} %{RELEASE}\n', '/etc/redhat-release'],
                stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                stderr=subprocess.PIPE, close_fds=True)
            out, err = p.communicate()
            if p.returncode == 0:
                version, release = out.split()
            else:
                version = release = ''


Version-Release number of selected component (if applicable):
vdsm-4.9-106.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.install more then a single redhat-release package
2.
3.
  
Actual results:
vdsmd fails to start

Expected results:


Additional info: