# Circle.yml for testing python3 with Ubuntu 14.04
machine:
  environment:
    REQUESTED_PYTHON_VER: 3.5.1
    SRC_PREFIX_DIR: ${HOME}/src
    INSTALL_PREFIX_DIR: ${HOME}/opt
    PATH: ${INSTALL_PREFIX_DIR}/Python-3.5.1/bin:${PATH}

dependencies:
  cache_directories:
    #- ${INSTALL_PREFIX_DIR}
    - ~/opt

  pre:
    # Install python3 from sources
    # REQUESTED_PYTHON_VER set in machine.environment
    - ./python_install.sh

test:
  pre:
    - which python
    - python --version
    - which python2
    - python2 --version
    - which python3
    - python3 --version

  override:
    - python3 -c 'print("OK")'

# Circle.yml for testing python3 with Ubuntu 14.04
machine:
  pre:
    - rm .python-version

  python:
    version: 3.5.1

test:
  pre:
    - which python
    - python --version
    - which python2
    - python2 --version
    - which python3
    - python3 --version

  override:
    - python3 -c 'print("OK")'

Delete .python-version and request version 3.5.1
Delete .python-version and request version 3.5.1

This is the work-around suggested by Hirokuni Kim from CircleCI.
