Re: pg12 rc1 on CentOS8 depend python2

> Users of these (now contrib) modules need to have
> postgresql12-plpython3 installed anyway, so it's unlikely you'd be
> breaking anyone's installation.

I agree.
To use these EXTENSION(hstore_plpython,jsonb_plpython, and ltree_plpython),
we need to install plpythonu anyway.
I don't think it would be a problem to move these EXTENSIONs to the
plpython package.

By using the rpm "--nodeps" option,
PostgreSQL 12 could be installed on CentOS8 where python2 is not installed.

# rpm -ivh --nodeps *
1:postgresql12-libs-12.0-1PGDG.rhel################################# [
20%]
2:postgresql12-12.0-1PGDG.rhel8 ################################# [
40%]
3:postgresql12-contrib-12.0-1PGDG.r################################# [
60%]
4:postgresql12-server-12.0-1PGDG.rh################################# [
80%]
5:postgresql12-docs-12.0-1PGDG.rhel#################################
[100%]

plpython could be installed in the same way.

# rpm -ivh --nodeps postgresql12-plpython-12.0-1PGDG.rhel8.x86_64.rpm
1:postgresql12-plpython-12.0-1PGDG.#################################
[100%]

Of course, "CREATE EXTENSION plpythonu" has caused an ERROR because CentOS8
isn't installed python2.

postgres=# CREATE EXTENSION plpythonu;
ERROR: could not load library "/usr/pgsql-12/lib/plpython2.so":
libpython2.7.so.1.0: cannot open shared object file: No such file or
directory postgres=#

"CREATE EXTENSION hstore_plpython2u" has caused an ERROR because required
"plpython2u".

postgres=# CREATE EXTENSION hstore_plpython2u;
ERROR: required extension "plpython2u" is not installed
HINT: Use CREATE EXTENSION ... CASCADE to install required extensions too.

By the way, "python2-libs is needed" error has occurred when
"postgresql12-12.0-1PGDG.rhel8.x86_64.rpm" and
"postgresql12-libs-12.0-1PGDG.rhel8.x86_64.rpm" install.

# rpm -ivh postgresql12-12.0-1PGDG.rhel8.x86_64.rpm
postgresql12-libs-12.0-1PGDG.rhel8.x86_64.rpm
error: Failed dependencies:
python2-libs is needed by postgresql12-12rc1-1PGDG.rhel8.x86_64

In this case, I think that python2-libs is not necessary.

Best Regards.
Keisuke Kuroda