I'm getting a similar bug when I try to install Bazaar gtk-3. When I run software-center-gtk3 from the command line, I get the following output:


someone@someone-UBook:~$ software-center-gtk3 
2012-02-25 01:34:10,510 - softwarecenter.ui.gtk3.em - INFO - EM's: 17 15 21
2012-02-25 01:34:11,699 - softwarecenter.ui.gtk3.utils - INFO - Softwarecenter style provider for adwaita Gtk theme: /usr/share/software-center/ui/gtk3/css/softwarecenter.css
2012-02-25 01:34:13,003 - softwarecenter.backend.spawn_helper - WARNING - exit code 1 from helper
2012-02-25 01:34:13,004 - softwarecenter.backend.spawn_helper - WARNING - got error from helper: 'ERROR:__main__:available_apps
Traceback (most recent call last):
  File "/usr/share/software-center/piston_get_scagent_available_apps.py", line 148, in <module>
    piston_reply = scaclient.available_apps(**kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 120, in wrapper
    body = func(self, *args, **kwargs)
  File "/usr/share/software-center/softwarecenter/backend/piston/scaclient_pristine.py", line 22, in available_apps
    scheme=PUBLIC_API_SCHEME)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 321, in _get
    headers=headers)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 474, in _request
    method=method, body=body, headers=headers)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1374, in request
    raise RedirectLimit("Redirected more times than rediection_limit allows.", {}, "")
RedirectLimit: Redirected more times than rediection_limit allows.
'
2012-02-25 01:34:13,004 - softwarecenter.db.update - WARNING - error: ERROR:__main__:available_apps
Traceback (most recent call last):
  File "/usr/share/software-center/piston_get_scagent_available_apps.py", line 148, in <module>
    piston_reply = scaclient.available_apps(**kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/validators.py", line 41, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 120, in wrapper
    body = func(self, *args, **kwargs)
  File "/usr/share/software-center/softwarecenter/backend/piston/scaclient_pristine.py", line 22, in available_apps
    scheme=PUBLIC_API_SCHEME)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 321, in _get
    headers=headers)
  File "/usr/lib/python2.7/dist-packages/piston_mini_client/__init__.py", line 474, in _request
    method=method, body=body, headers=headers)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1375, in request
    (response, new_content) = self.request(info['-x-permanent-redirect-url'], "GET", headers = headers, redirections = redirections - 1)
  File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1374, in request
    raise RedirectLimit("Redirected more times than rediection_limit allows.", {}, "")
RedirectLimit: Redirected more times than rediection_limit allows.

2012-02-25 01:34:13,571 - softwarecenter.ui.gtk3.app - INFO - software-center-agent finished with status 1
2012-02-25 01:34:26,669 - softwarecenter.backend - WARNING - _on_trans_error: org.freedesktop.PolicyKit.Error.Failed: ('system-bus-name', {'name':  ':1.1137'}): org.debian.apt.install-or-remove-packages
/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py:304: Warning: g_object_ref: assertion `G_IS_OBJECT (object)' failed
  context.iteration()

** (software-center-gtk3:4736): CRITICAL **: atk_object_ref_state_set: assertion `ATK_IS_OBJECT (accessible)' failed