Allow venv python interpreter to be overridden

Change-Id: I7d5cfc8f07b92a71150a189eb352b8a02051c0c9

defaults/main.yml

@@ -33,6 +33,7 @@ swift_pip_package_state: "latest"
 
 # Set installation method.
 swift_install_method: "source"
+swift_venv_python_executable: "{{ openstack_venv_python_executable | default('python2') }}"
 
 # Git repo details for swift
 swift_git_repo: https://git.openstack.org/openstack/swift

tasks/swift_install.yml

@@ -40,6 +40,7 @@
   import_role:
     name: "python_venv_build"
   vars:
+    venv_python_executable: "{{ swift_venv_python_executable }}"
     venv_build_constraints: "{{ swift_git_constraints }}"
     venv_build_distro_package_list: "{{ swift_devel_distro_packages }}"
     venv_install_destination_path: "{{ swift_bin | dirname }}"