Comment 7 for bug 1031274

I think this should be fixed with a recent upload of network-manager:

 network-manager (0.9.6.0~git201207271115.edb85e9-0ubuntu4) quantal; urgency=low
 .
   * debian/tests/nm, debian/tests/dnsmasq: run ifblacklist_migrate.sh while
     setting up the tests; so that we have some devices we can manage and use
     to get proper data for the tests.
   * debian/patches/dnsmasq-dbus-updates.patch: don't crash when building the
     dbus message for updating dnsmasq's nameservers. (LP: #1031274)

See https://launchpad.net/ubuntu/+source/network-manager/0.9.6.0~git201207271115.edb85e9-0ubuntu4.

Sorry for the inconvenience. Since this should cover your issue, I'll mark this bug as Fix Released. Please feel free to reopen or file a new bug if there are any further issues.