I can *not* reproduce the problem with Python 2.6 (with its stock bsddb
version) and Berkeley DB 4.7.25 (the current one).

I can reproduce the issue if I use Berkeley DB 4.6.21. Seems to be a
(solved) problem in the library.

Berkeley DB 4.7.25 is known to solve a few memory leaks:
http://www.oracle.com/technology/documentation/berkeley-db/db/ref/changelog/4.7.html

I mark the bug as "closed" and "out of date" because it is no something
we can solve and it is already resolved in BDB 4.7.25, published a year ago.

Moreover, any serious usage of Berkeley DB "demands" a recent version of
the library.