When running the test_xmlrpc unittest not against the anydbm backend, but against postgresql, several problems become visible.

To change the backend to postgresql, you can either:

* in the unittest class, add a second parameter: `db_test_base.setupTracker(self.dirname, "postgresql")` or
* apply SF patch #1893839, which modifies the unittest to run against all available backends.

After the change, you can see the following problems:

1)  For all transaction-aware backends, modifications to items are not committed to the database, e.g.:

testChange (test.test_xmlrpc.TestCase_sqlite) ... 
[...]
AssertionError: 'Joe Random' != 'Joe Doe'


2)  db_test_base.setupTracker doesn't create a valid postgresql installation if the database already exists:

IOError: [Errno 2] No such file or directory: '_test_xmlrpc/db/backend_name'


3) and if you solve 2, you see that xmlrpc.RoundupServer doesn't close the database handler in same use-cases, e.g., after 

testAuthDeniedEdit 

the next testcase will always fail with:

Error in test testAuthDeniedEdit 
[...]
RuntimeError: 10 attempts to create database failed

because the database is still open.