Comment 13 for bug 1085425

After upgrading to ubuntu 13.04, i have the same problem here. I have no zope package in my python dist packages.

~$ software-center
2013-04-27 05:56:26,937 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2013-04-27 05:56:27,229 - softwarecenter.fixme - WARNING - logs to the root logger: '('/usr/lib/python2.7/dist-packages/dbus/proxies.py', 410, '_introspect_error_handler')'
2013-04-27 05:56:27,229 - dbus.proxies - ERROR - Introspect error on com.ubuntu.sso:/com/ubuntu/sso/credentials: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ChildExited: Process /usr/lib/ubuntu-sso-client/ubuntu-sso-login exited with status 1
Traceback (most recent call last):
  File "/usr/bin/software-center", line 130, in <module>
    app = SoftwareCenterAppGtk3(options, args)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 338, in __init__
    self.icons)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/session/appmanager.py", line 66, in __init__
    self.oauth_token = helper.find_oauth_token_sync()
  File "/usr/share/software-center/softwarecenter/backend/ubuntusso.py", line 141, in find_oauth_token_sync
    sso.find_credentials()
  File "/usr/share/software-center/softwarecenter/backend/login_impl/login_sso.py", line 75, in find_credentials
    self.proxy.find_credentials(self.appname, self._get_params())
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ChildExited: Process /usr/lib/ubuntu-sso-client/ubuntu-sso-login exited with status 1

~$ /usr/lib/ubuntu-sso-client/ubuntu-sso-login
Traceback (most recent call last):
  File "/usr/lib/ubuntu-sso-client/ubuntu-sso-login", line 67, in <module>
    from ubuntu_sso.main import main
  File "/usr/lib/python2.7/dist-packages/ubuntu-sso-client/ubuntu_sso/main/__init__.py", line 42, in <module>
    from ubuntu_sso.account import Account
  File "/usr/lib/python2.7/dist-packages/ubuntu-sso-client/ubuntu_sso/account.py", line 48, in <module>
    from ubuntu_sso.utils.webclient.common import WebClientError
  File "/usr/lib/python2.7/dist-packages/ubuntu-sso-client/ubuntu_sso/utils/webclient/common.py", line 34, in <module>
    from oauthlib.oauth1 import (
ImportError: cannot import name SIGNATURE_HMAC