CI/travis/macOS: fix missing pip3

homebrew or Travis changed something, now `pip3` isn't in $PATH.
`ls /usr/local/opt/python/libexec/bin` confirmed this, no matter what
brew reinstall/relink/upgrade are used.

Bumping the macOS image to 10.12 or 10.13 makes the problem go away.

    ==> Processing gcc49 formula rename to gcc@4.9
    ==> Unlinking gcc49
    ==> Moving gcc49 versions to /usr/local/Cellar/gcc@4.9
    ==> Relinking gcc@4.9
    Warning: gcc@4.9 is outdated!
    To avoid broken installations, as soon as possible please run:
      brew upgrade
    Or, if you're OK with a less reliable fix:
      brew upgrade gcc@4.9
    python info:
      Python 2.7.12
      Python 2.7.12
      ci/before_install.sh: line 18: python3: command not found
      pip 8.1.2 from /usr/local/lib/python2.7/site-packages (python 2.7)
      pip 8.1.2 from /usr/local/lib/python2.7/site-packages (python 2.7)
      ci/before_install.sh: line 21: pip3: command not found
      pyenv versions:
      * system (set by /Users/travis/.pyenv/version)
    Upgrade Python 3.
    To restore the stashed changes to /usr/local/Homebrew run:
      'cd /usr/local/Homebrew && git stash pop'
    ==> Caveats
    Python has been installed as
      /usr/local/bin/python3
    Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
    `python3`, `python3-config`, `pip3` etc., respectively, have been installed into
      /usr/local/opt/python/libexec/bin
    If you need Homebrew's Python 2.7 run
      brew install python@2
    Pip, setuptools, and wheel have been installed. To update them run
      pip3 install --upgrade pip setuptools wheel
    You can install Python packages with
      pip3 install <package>
    They will install into the site-package directory
      /usr/local/lib/python3.7/site-packages
    See: https://docs.brew.sh/Homebrew-and-Python
    ==> Summary
    º  /usr/local/Cellar/python/3.7.0: 8,864 files, 153.8MB, built in 6 minutes 32 seconds
    ...
    Upgrade Python 3 pip.
    ci/before_install.sh: line 30: pip3: command not found
    travis_time:end:0d23f522:start=1538818824750644000,finish=1538819451424021000,duration=626673377000
    The command "ci/before_install.sh" failed and exited with 127 during .
    Your build has been stopped.
    /Users/travis/.travis/job_stages: line 373: shell_session_update: command not found

    ==> Processing gcc49 formula rename to gcc@4.9
    ==> Unlinking gcc49
    ==> Moving gcc49 versions to /usr/local/Cellar/gcc@4.9
    ==> Relinking gcc@4.9
    Warning: gcc@4.9 is outdated!
    To avoid broken installations, as soon as possible please run:
      brew upgrade
    Or, if you're OK with a less reliable fix:
      brew upgrade gcc@4.9
    python info:
      Python 2.7.12
      Python 2.7.12
      ci/before_install.sh: line 18: python3: command not found
      pip 8.1.2 from /usr/local/lib/python2.7/site-packages (python 2.7)
      pip 8.1.2 from /usr/local/lib/python2.7/site-packages (python 2.7)
      ci/before_install.sh: line 21: pip3: command not found
      pyenv versions:
      * system (set by /Users/travis/.pyenv/version)
    Upgrade Python 3.
    To restore the stashed changes to /usr/local/Homebrew run:
      'cd /usr/local/Homebrew && git stash pop'
    ==> Caveats
    Python has been installed as
      /usr/local/bin/python3
    Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
    `python3`, `python3-config`, `pip3` etc., respectively, have been installed into
      /usr/local/opt/python/libexec/bin
    If you need Homebrew's Python 2.7 run
      brew install python@2
    Pip, setuptools, and wheel have been installed. To update them run
      pip3 install --upgrade pip setuptools wheel
    You can install Python packages with
      pip3 install <package>
    They will install into the site-package directory
      /usr/local/lib/python3.7/site-packages
    See: https://docs.brew.sh/Homebrew-and-Python
    ==> Summary
    º  /usr/local/Cellar/python/3.7.0: 8,864 files, 153.8MB, built in 6 minutes 32 seconds
    ...
    Upgrade Python 3 pip.
    ci/before_install.sh: line 30: pip3: command not found
    travis_time:end:0d23f522:start=1538818824750644000,finish=1538819451424021000,duration=626673377000
    The command "ci/before_install.sh" failed and exited with 127 during .
    Your build has been stopped.
    /Users/travis/.travis/job_stages: line 373: shell_session_update: command not found

3 files changed, 11 insertions, 11 deletions

diff --git a/.travis.yml b/.travis.yml
index fa884bd021..8ad9d7a6fb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -69,10 +69,10 @@ jobs:
       env: BUILD_32BIT=ON
     - os: osx
       compiler: clang
-      osx_image: xcode7.3  # macOS 10.11
+      osx_image: xcode9.4  # macOS 10.13
     - os: osx
       compiler: gcc
-      osx_image: xcode7.3  # macOS 10.11
+      osx_image: xcode9.4  # macOS 10.13
     - os: linux
       env: CI_TARGET=lint
     - stage: Flaky builds
diff --git a/ci/before_install.sh b/ci/before_install.sh
index 9a3e192536..6610d7d3d5 100755
--- a/ci/before_install.sh
+++ b/ci/before_install.sh
@@ -9,6 +9,8 @@ fi
 
 if [[ "${TRAVIS_OS_NAME}" == osx ]]; then
   brew update
+  echo "Upgrade Python 3"
+  brew upgrade python
 fi
 
 echo 'python info:'
@@ -24,17 +26,15 @@ echo 'python info:'
 ) | sed 's/^/  /'
 
 if [[ "${TRAVIS_OS_NAME}" == osx ]]; then
-  echo "Upgrade Python 3."
-  brew upgrade python
-  echo "Upgrade Python 3 pip."
+  echo "Upgrade Python 3 pip"
   pip3 -q install --user --upgrade pip
 else
-  echo "Upgrade Python 2 pip."
-  pip2.7 -q install --user --upgrade pip
-  echo "Upgrade Python 3 pip."
+  echo "Upgrade Python 2 pip"
+  python2.7 -m pip -q install --user --upgrade pip
+  echo "Upgrade Python 3 pip"
   # Allow failure. pyenv pip3 on travis is broken:
   # https://github.com/travis-ci/travis-ci/issues/8363
-  pip3 -q install --user --upgrade pip || true
+  python3 -m pip -q install --user --upgrade pip || true
 fi
 
 echo "Install node (LTS)"
diff --git a/ci/install.sh b/ci/install.sh
index e95e2f29c1..2cb8e78e67 100755
--- a/ci/install.sh
+++ b/ci/install.sh
@@ -18,14 +18,14 @@ fi
 echo "Install neovim module for Python 3."
 # Allow failure. pyenv pip3 on travis is broken:
 # https://github.com/travis-ci/travis-ci/issues/8363
-CC=cc pip3 -q install --user --upgrade neovim || true
+CC=cc python3 -m pip -q install --user --upgrade neovim || true
 
 if ! [ "${TRAVIS_OS_NAME}" = osx ] ; then
   # Update PATH for pip.
   export PATH="$(python2.7 -c 'import site; print(site.getuserbase())')/bin:$PATH"
   # Use default CC to avoid compilation problems when installing Python modules.
   echo "Install neovim module for Python 2."
-  CC=cc pip2.7 -q install --user --upgrade neovim
+  CC=cc python2.7 -m pip -q install --user --upgrade neovim
 
   echo "Install neovim RubyGem."
   gem install --no-document --version ">= 0.2.0" neovim