Improve checking for pg_index.xmin

When Who What
2020-03-24 22:27:46 Alexander Korotkov (smagen) Closed in commitfest 2020-03 with status: Returned with feedback
2020-02-01 12:43:27 Tomas Vondra (fuzzycz) Closed in commitfest 2020-01 with status: Moved to next CF
2019-11-29 06:03:58 Michael Paquier (michael-kun) Closed in commitfest 2019-11 with status: Moved to next CF
2019-10-31 23:52:04 Alexander Korotkov (smagen) Changed authors to Alexander Korotkov (smagen)
2019-10-31 23:51:54 Alexander Korotkov (smagen) Attached mail thread CAPpHfduk5Kh1bF9-8Xovgq78k9LyRUodFsfbmSAFuA_5kwbCPA@mail.gmail.com
2019-10-31 23:51:54 Alexander Korotkov (smagen) Created patch record