Comment 1 for bug 265860

'move_list' was removed in Mailman 2.1 (somewhere before
Mailman 2.1a2 in fact), so you shouldn't have it, let alone
use it. The error you're getting suggests you are using an
ancient version of Python: it chokes on the use of
augmented assignment, which was added in Python 2.0. Mailman
2.1 requires Python 2.1 or higher.