software-center-gtk3 crashed with AttributeError in on_window_main_key_press_event(): 'AvailablePane' object has no attribute 'navigation_bar'

Description: Ubuntu oneiric (development branch)
Release: 11.10
software-center:
  Installed: 4.1.20
  Candidate: 4.1.20
  Version table:
 *** 4.1.20 0
        500 http://in.archive.ubuntu.com/ubuntu/ oneiric/main i386 Packages
        100 /var/lib/dpkg/status
Expected Outcome: There should have been no crash reported.
Actual Outcome: A crash was reported when I switched between the All Software tab and the Progress tab.

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: software-center 4.1.20
ProcVersionSignature: Ubuntu 3.0.0-9.15-generic 3.0.3
Uname: Linux 3.0.0-9-generic i686
Architecture: i386
Date: Thu Sep 1 18:13:41 2011
EcryptfsInUse: Yes
ExecutablePath: /usr/share/software-center/software-center-gtk3
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta i386 (20110831)
InterpreterPath: /usr/bin/python2.7
PackageArchitecture: all
ProcCmdline: /usr/bin/python /usr/bin/software-center-gtk3
PythonArgs: ['/usr/bin/software-center-gtk3']
SourcePackage: software-center
Title: software-center-gtk3 crashed with AttributeError in on_window_main_key_press_event(): 'AvailablePane' object has no attribute 'navigation_bar'
Traceback:
 Traceback (most recent call last):
   File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 469, in on_window_main_key_press_event
     not self.active_pane.navigation_bar.has_id(NavButtons.ID_PURCHASE)):
 AttributeError: 'AvailablePane' object has no attribute 'navigation_bar'
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare