Database version upgrade from postgresql 12 to postgresql 13 is not working

[dinaharan]

I was trying to test postgresql upgrade to version 13 from version 12 using RHEL8 based image but it's not working. I see the following env is missing in RHEL8 based postgresql 13 Dockerfile.

POSTGRESQL_PREV_VERSION=12

Here is the link to problematic Dockerfile.

https://github.com/sclorg/postgresql-container/blob/generated/13/Dockerfile.rhel8

I tried the same upgrade using RHEL7 based image and it works fine.

[dinaharan]

PR #451 submitted for this issue.