--pg-extensions appear not to work with CircleCI

[tnigon]

--pg-extensions appear not to work with CircleCI.

Locally, the pytest --pg-extension-postgis command works fine, but when running the command via CircleCI config, I get the following error:

../miniconda/envs/test/lib/python3.8/site-packages/sqlalchemy/engine/base.py:1283: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
 
self = <sqlalchemy.dialects.postgresql.psycopg2.PGDialect_psycopg2 object at 0x7f70ac219d00>
cursor = <cursor object at 0x7f7105d5c4f0; closed: -1>
statement = 'BEGIN TRANSACTION; CREATE EXTENSION IF NOT EXISTS "postgis"; COMMIT;'
parameters = {}
context = <sqlalchemy.dialects.postgresql.psycopg2.PGExecutionContext_psycopg2 object at 0x7f7105d01e20>
    def do_execute(self, cursor, statement, parameters, context=None):
>       cursor.execute(statement, parameters)
E       psycopg2.errors.UndefinedFile: could not open extension control file "/home/circleci/miniconda/envs/test/share/extension/postgis.control": No such file or directory
../miniconda/envs/test/lib/python3.8/site-packages/sqlalchemy/engine/default.py:590: UndefinedFile

It seems to be caused by my CircleCI directory path, but I am having troubles looking into this deeper without being able to do it locally (it's on the CircleCI server instead). In other words, why isn't "postgis.control" file in /home/circleci/miniconda/envs/test/share/extension/?

The tests run and pass just fine when I remove the --pg-extensions option. Is the best option just to install the extensions via postgresql_db.install_extension('postgis')?

Here is my CircelCi config.yml:

version: 2.1

orbs:
  python: circleci/python@0.2.1

jobs:
  build-and-test:
    working_directory: ~/db
    docker:
      - image: circleci/python:3.8.2
      - image: circleci/postgres:9.6-postgis-ram
        environment:
          POSTGRES_USER: 'postgres'
          POSTGRES_PASSWORD: 'password'
          POSTGRES_DB: test_db
    steps:
      - checkout
      - run:
          name: Install dependencies
          command: |
             wget https://repo.anaconda.com/miniconda/Miniconda2-latest-Linux-x86_64.sh -O miniconda.sh
             bash miniconda.sh -b -p "$HOME"/miniconda
             source /home/circleci/miniconda/etc/profile.d/conda.sh
             conda activate base
             conda config --set always_yes yes --set auto_update_conda false
             conda update conda
             # Create test environment
             conda create -n test python=$PYTHON_VERSION
             conda activate test
             conda config --env --add channels conda-forge
             conda install -n test --file requirements/testing.txt
             pip install -r requirements/testing_pip.txt
      - run:
          name: Conda information
          command: |
             source /home/circleci/miniconda/etc/profile.d/conda.sh
             conda activate test
             conda info
             conda config --show
             conda list --show-channel-urls
      - run:
          name: Run tests
          command: |
             source /home/circleci/miniconda/etc/profile.d/conda.sh
             conda activate test
             mkdir test-results
             # pytest --pg-extensions=postgis--junitxml=test-results/junit.xml --cov=db --cov-report=xml  # doesn't work
             pytest --junitxml=test-results/junit.xml --cov=db --cov-report=xml  # works