The test set of PG96 needs to be updated.

[qianglingjie]

Same as 8286b67 commit postgres/postgres@37681d7 has also changed the core's behavior of naming indexes in PG96. However, branch PG96 have not follow the mentioned behavioral change above yet, so I think it is necessary to update branch PG96's master log like other branches.

[horiguti]

There can be a case where the PostgreSQL side change cusae the regression tests fail. But I don't want to maintain followng every PostgreSQL behavioral change. Addition to that, PG96 is log ago EOLed. Sorry but I won't do that except when some serious bug is fixed.