Support target_session_attrs=read-only and eliminate the added round-trip to detect session status.

When Who What
2018-09-24 21:15:42 Elvis Pranskevichus (elprans) Deleted annotation "New patch revision" from 2239254.dtfY1H9x0t@hammer.magicstack.net
2018-09-24 16:36:36 Elvis Pranskevichus (elprans) Added annotation "New patch revision" to 2239254.dtfY1H9x0t@hammer.magicstack.net
2018-03-01 09:25:31 Andres Freund (andresfreund) Closed in commitfest 2018-03 with status: Returned with feedback
2018-02-28 07:59:20 Takayuki Tsunakawa (maumau) New status: Waiting on Author
2018-02-28 07:58:50 Takayuki Tsunakawa (maumau) Changed authors to Takayuki Tsunakawa (maumau)
2018-02-28 07:58:37 Takayuki Tsunakawa (maumau) Attached mail thread 1700970.cRWpxnom9y@hammer.magicstack.net
2018-02-28 07:58:37 Takayuki Tsunakawa (maumau) Created patch record