BUG #17281: How specify regress database?

The following bug has been logged on the website:

Bug reference:      17281
Logged by:          RekGRpth
Email address:      rekgrpth@gmail.com
PostgreSQL version: 14.0
Operating system:   docker alpine
Description:

I try
1) add in Makefile
CONTRIB_TESTDB = postgres
2) add in Makefile
REGRESS_OPTS = --use-existing --dbname=postgres
3) add in Makefile
EXTRA_REGRESS_OPTS = --use-existing --dbname=postgres
4) before calling make installcheck
export CONTRIB_TESTDB=postgres
but results everything is same:
/usr/lib/postgresql/pgxs/src/makefiles/../../src/test/regress/pg_regress
--inputdir=./ --bindir='/usr/bin'    --use-existing --dbname=postgres
--dbname=contrib_regression extension
i.e. pgxs places --dbname=contrib_regression in last option due to
https://www.postgresql.org/message-id/flat/14108.1314148639%40sss.pgh.pa.us