From Mainlog we can see the following:
2012-09-05 19:34:49,554 INFO apt version: '0.8.16~exp12ubuntu10.3' 2012-09-05 19:34:49,555 INFO release-upgrader version '0.180' started
That version of apt should have contained the fix for bug 927993, but perhaps it was insufficient.
From Mainlog we can see the following:
2012-09-05 19:34:49,554 INFO apt version: '0.8.16~ exp12ubuntu10. 3'
2012-09-05 19:34:49,555 INFO release-upgrader version '0.180' started
That version of apt should have contained the fix for bug 927993, but perhaps it was insufficient.