use binaries for Python on mac

instead of building from source with pipenv

saves several minutes

.travis.yml

@@ -1,5 +1,6 b''
 # http://travis-ci.org/#!/ipython/ipython
 language: python
+os: linux
 
 addons:
     apt:
@@ -21,17 +22,19 b' group: edge'
 before_install:
     - 'if [[ $GROUP != js* ]]; then COVERAGE=""; fi'
     - |
+    # install Python on macOS
       if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-        brew update
-        brew upgrade pyenv
-        eval "$(pyenv init -)"
-        pyenv install --skip-existing "$PYENV_VERSION"
-        pyenv global "$PYENV_VERSION"
-        pyenv rehash
+      env | sort
+      if ! which python$TRAVIS_PYTHON_VERSION; then
+        HOMEBREW_NO_AUTO_UPDATE=1 brew tap minrk/homebrew-python-frameworks
+        HOMEBREW_NO_AUTO_UPDATE=1 brew cask install python-framework-${TRAVIS_PYTHON_VERSION/./}
+      fi
+      python3 -m pip install virtualenv
+      python3 -m virtualenv -p $(which python$TRAVIS_PYTHON_VERSION) ~/travis-env
+      source ~/travis-env/bin/activate
       fi
     - python --version
 
-
 install:
     - pip install pip --upgrade
     - pip install setuptools --upgrade
@@ -62,12 +65,23 b' after_success:'
 
 matrix:
     include:
-        - { python: "3.6-dev", dist: xenial, sudo: true, os: linux }
-        - { python: "3.7", dist: xenial, sudo: true, os: linux }
-        - { python: "3.7-dev", dist: xenial, sudo: true, os: linux }
-        - { python: "nightly", dist: xenial, sudo: true, os: linux }
-        - { os: osx, language: generic, env: TRAVIS_PYTHON_VERSION="3.6" PYENV_VERSION="3.6.7" }
-        - { os: osx, language: generic, env: TRAVIS_PYTHON_VERSION="3.7" PYENV_VERSION="3.7.1" }
+    - python: "3.7"
+      dist: xenial
+      sudo: true
+    - python: "3.7-dev"
+      dist: xenial
+      sudo: true
+    - python: "nightly"
+      dist: xenial
+      sudo: true
+    - os: osx
+      language: generic
+      python: 3.6
+      env: TRAVIS_PYTHON_VERSION=3.6
+    - os: osx
+      language: generic
+      python: 3.7
+      env: TRAVIS_PYTHON_VERSION=3.7
     allow_failures:
         - python: nightly