[PEAK] _startDBTxn

[Erik Rose]

> Neither, as far as I can recall.  :)  _startDBTxn() is used only for 
> databases that don't enter transactions automatically.  IIRC, with 
> PostgreSQL DBAPI adapters, when you commit or abort a transaction, a 
> new one is automatically started.

Ah, good point! Postgres itself defaults to statement-by-statement 
autocommit mode, but psycopg does explicitly send a "begin". I'd forgot 
about that layer. Thanks!