[stable-2.10] Fix ansible-test virtualenv management.

(cherry picked from commit 1e02a201a6)

Co-authored-by: Matt Clay <matt@mystile.com>

changelogs/fragments/ansible-test-virtualenv-fix.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - ansible-test now always uses the ``--python`` option for ``virtualenv`` to select the correct interpreter when creating environments with the ``--venv`` option

test/lib/ansible_test/_internal/venv.py

@@ -173,10 +173,9 @@ def run_virtualenv(args,  # type: EnvironmentConfig
                    path,  # type: str
                    ):  # type: (...) -> bool
     """Create a virtual environment using the 'virtualenv' module."""
-    cmd = [run_python, '-m', 'virtualenv']
-
-    if run_python != env_python:
-        cmd += ['--python', env_python]
+    # always specify --python to guarantee the desired interpreter is provided
+    # otherwise virtualenv may select a different interpreter than the one running virtualenv
+    cmd = [run_python, '-m', 'virtualenv', '--python', env_python]
 
     if system_site_packages:
         cmd.append('--system-site-packages')