crontabberise drop_old_partitions; bug 1014128; attempt #2

This addresses bug 1014128. Again. (Previous attempt at rebasing was a horrible disaster. :unamused:) 

`?r` @peterbe and/or @rhelmer :revolving_hearts: 
This is mentioned in http://legacy.python.org/dev/peps/pep-0249/#Cursor.close but in a roundabout way:
"Close the cursor now (rather than whenever __del__ is called)."