Incorrect wal_archive command by default #4
Description
In the Setting Up WAL Archiving section of this page: http://www.postgresql.org/docs/9.2/static/continuous-archiving.html it makes clear that the archive_command should test the file to ensure that it only returns a nonzero status if the file was successfully copied, and did not already exist (for data integrity reasons). That is currently not the case here: https://github.com/pallet/postgres-crate/blob/develop/src/pallet/crate/postgres.clj#L495