Fix Python 3.5 MacOS wheel upload

Python 3.5 on Mac OS doesn't support TLS 1.2, which makes twine upload
fail, but we can use system Python 2.7 for twine upload, which works.

Also brings the rest of the Travis CI configuration closer in line to
the rest of the packages updated for
https://github.com/zopefoundation/meta/issues/11

.travis.yml

@@ -2,9 +2,9 @@ language: python
 
 env:
   global:
-    - TWINE_USERNAME: zope.wheelbuilder
-    # this sets $PYPIPASSWORD
-    - secure: "Oh5gRJ+Fo8ZNmCkdrffpx201EPyTr9iUXmv6VqJMTebrzQpFdSWUVcANRmAzyfdyk3Wo0IjifVfWsKc+hvtbFmXZiLRFyEgoCUmzeWVumjebg2xxm0PbFHcRQgl4daBXxB0iqWkP8wXZ3daytuL74sYcbHizMYyhc7AxFbANsZc="
+    TWINE_USERNAME: zope.wheelbuilder
+    TWINE_PASSWORD:
+      secure: "GoACBHy175St7lL5BIfW6Jz4HLG7XWpyt8znNJPe1HwInjSOWRqc0EZGVAjpCfOGX3iE3HchDH00WydkPuYEgUo0eoH59vVKk+x+LccKmUPQBSBW4HN40UVgQhtMm3BFsdk+dq0taxw2ZNGmv0+uo9uLqVXkcNNpokmOyoXkDmc="
 
 python:
   - 2.7
@@ -78,25 +78,36 @@ install:
   - pip install -e .[test,ZODB]
 
 script:
+  - python --version
   - |
     if [[ "$WITH_COVERAGE" == "1" ]]; then
       coverage run -m zope.testrunner --test-path=. --auto-color --auto-progress --verbose
     else
       zope-testrunner --test-path=. --auto-color --auto-progress --verbose
     fi
+  - python setup.py -q bdist_wheel
 
 after_success:
   - if [[ "$WITH_COVERAGE" == "1" ]]; then coveralls; fi
   - |
-    if [[ $TRAVIS_TAG && "$TRAVIS_OS_NAME" == "osx" ]]; then
-      pip install twine
-      python setup.py bdist_wheel
-      TWINE_PASSWORD=$PYPIPASSWORD twine upload --skip-existing dist/*
+    if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
+      # macpython 3.5 doesn't support recent TLS protocols which causes twine
+      # upload to fail, so we use the system Python to run twine
+      /usr/bin/python -m ensurepip --user
+      /usr/bin/python -m pip install --user -U pip
+      /usr/bin/python -m pip install --user -U -I twine
+      /usr/bin/python -m twine check dist/*
+      if [[ $TRAVIS_TAG ]]; then
+        /usr/bin/python -m twine upload --skip-existing dist/*
+      fi
     fi
   - |
-    if [[ $TRAVIS_TAG && -n "$DOCKER_IMAGE" ]]; then
+    if [[ -n "$DOCKER_IMAGE" ]]; then
       pip install twine
-      TWINE_PASSWORD=$PYPIPASSWORD twine upload --skip-existing wheelhouse/*
+      twine check wheelhouse/*
+      if [[ $TRAVIS_TAG ]]; then
+        twine upload --skip-existing wheelhouse/*
+      fi
     fi
 
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