Set PYTHONNOUSERSITE=1 [azure parallel] [doc build]

Author: lesteve

.circleci/config.yml

@@ -24,6 +24,8 @@ jobs:
       - OPENBLAS_NUM_THREADS: 2
       - CONDA_ENV_NAME: testenv
       - LOCK_FILE: build_tools/circle/doc_min_dependencies_linux-64_conda.lock
+      # Avoid using Python packages installed in the Docker image inside ~/.local/lib
+      - PYTHONNOUSERSITE: 1
       # Do not fail if the documentation build generates warnings with minimum
       # dependencies as long as we can avoid raising warnings with more recent
       # versions of the same dependencies.
@@ -62,6 +64,8 @@ jobs:
       - OPENBLAS_NUM_THREADS: 2
       - CONDA_ENV_NAME: testenv
       - LOCK_FILE: build_tools/circle/doc_linux-64_conda.lock
+      # Avoid using Python packages installed in the Docker image inside ~/.local/lib
+      - PYTHONNOUSERSITE: 1
       # Make sure that we fail if the documentation build generates warnings with
       # recent versions of the dependencies.
       - SKLEARN_WARNINGS_AS_ERRORS: '1'