Attempt to fix Travis for python 3.2 / pypy3-2.4

Author: behackett

.travis.yml

@@ -17,5 +17,7 @@ services:
 script: python setup.py test
 
 install:
-    # Temporary solution for Travis CI multiprocessing issue #943
+    # Work around https://github.com/travis-ci/travis-ci/issues/943
     - sudo rm -rf /dev/shm && sudo ln -s /run/shm /dev/shm
+    # Work around https://github.com/travis-ci/travis-ci/issues/5485
+    - travis_retry pip install "virtualenv<14.0.0"