Log Message:
Update to 2.6.1:

What's new in psycopg 2.6.1
^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Lists consisting of only `None` are escaped correctly (:ticket:`#285`).
- Fixed deadlock in multithread programs using OpenSSL (:ticket:`#290`).
- Correctly unlock the connection after error in flush (:ticket:`#294`).
- Fixed ``MinTimeLoggingCursor.callproc()`` (:ticket:`#309`).