Added checks for `--delta` and `--force` restore options to ensure that the destination is a valid $PGDATA directory. pgBackRest will check for the presence of `PG_VERSION` or `backup.manifest` (left over from an aborted restore). If neither is found then `--delta` and `--force` will be disabled but the restore will proceed unless there are files in the $PGDATA directory (or any tablespace directories) in which case the operation will be aborted.
When backing up and restoring tablespaces pgBackRest only operates on the subdirectory created for the version of PostgreSQL being run against. Since multiple versions can live in a tablespace (especially during a binary upgrade) this prevents too many files from being copied during a backup and other versions possibly being wiped out during a `--delta` restore. This only applies to PostgreSQL >= 9.0 -- before that only one PostgreSQL version could use a tablespace.
* Better messaging for expiration.
* Fixed already stopped message.
* retention-archive and retention-archive-type now use retention-full and 'full' when not specified.
* Fixed issue where backup-user was required (should default to backrest).
* ExecuteTest now supports retries.
* Fixed issue where log test was not comparing test logs.
* Fixed issue where test logs would not match for ssh connection errors
