Thanks for reporting. Now that I see you're using an old revision the answer is clear; this is indeed the python tarfile bug (http://bugs.python.org/issue23228).
We worked around this issue in ubuntu-core-upgrader package r52 (aka ubuntu-core-upgrader version 0.6~ppa18). So, if you have to use system-image r211, you'll probably want to rebuild lp:~snappy-dev/+junk/ubuntu-core-upgrader and install that.
Hi Martin,
Thanks for reporting. Now that I see you're using an old revision the answer is clear; this is indeed the python tarfile bug (http:// bugs.python. org/issue23228).
We worked around this issue in ubuntu- core-upgrader package r52 (aka ubuntu- core-upgrader version 0.6~ppa18). So, if you have to use system-image r211, you'll probably want to rebuild lp:~snappy-dev/+junk/ubuntu-core-upgrader and install that.