Managed to write a patch in PyPy that seems to pass all tests including the new one, including on Windows.  I know think that dd13098a5dc2 should be backed out (i.e. 030e100f048a should be kept).

Reference to the PyPy changes: https://bitbucket.org/pypy/pypy/commits/235e8a3889790042b3f148bcf04891b27f97a1fc

Maybe something similar should be added to CPython, to avoid the unexpected "database table is locked" case; but such a change should probably be done only in trunk, because the <= 2.6 experience seems to suggest it is rare enough in practice.