Try using the pip caching in the tox config.

.travis.yml

@@ -8,49 +8,40 @@ cache:
   directories:
     - ~/.cache/pip
 env:
-  global:
-    # These two environment variables could be set by Travis itself, or Travis
-    # could configure itself in /etc/, ~/, or inside of the virtual
-    # environments. In any case if these two values get configured then end
-    # users only need to enable the pip cache and manually run pip wheel before
-    # running pip install.
-    - PIP_WHEEL_DIR=$HOME/.cache/pip/wheels
-    - PIP_FIND_LINKS=file://$HOME/.cache/pip/wheels
-  matrix:
-    - TOXENV=flake8-py27
-    - TOXENV=flake8-py33
-    - TOXENV=py26-dj14
-    - TOXENV=py26-dj15
-    - TOXENV=py26-dj16
-    - TOXENV=pypy-dj14
-    - TOXENV=pypy-dj15
-    - TOXENV=pypy-dj16
-    - TOXENV=py27-dj14
-    - TOXENV=py27-dj15
-    - TOXENV=py27-dj16
-    - TOXENV=py27-dj17
-    - TOXENV=py27-dj18
-    - TOXENV=py27-dj19
-    - TOXENV=py32-dj15
-    - TOXENV=py32-dj16
-    - TOXENV=py32-dj17
-    - TOXENV=py32-dj18
-    - TOXENV=py32-dj19
-    - TOXENV=py33-dj15
-    - TOXENV=py33-dj16
-    - TOXENV=py33-dj17
-    - TOXENV=py33-dj18
-    - TOXENV=py33-dj19
-    - TOXENV=py34-dj15
-    - TOXENV=py34-dj16
-    - TOXENV=py34-dj17
-    - TOXENV=py34-dj18
-    - TOXENV=py34-dj19
-    - TOXENV=pypy-dj15
-    - TOXENV=pypy-dj16
-    - TOXENV=pypy-dj17
-    - TOXENV=pypy-dj18
-    - TOXENV=pypy-dj19
+  - TOXENV=flake8-py27
+  - TOXENV=flake8-py33
+  - TOXENV=py26-dj14
+  - TOXENV=py26-dj15
+  - TOXENV=py26-dj16
+  - TOXENV=pypy-dj14
+  - TOXENV=pypy-dj15
+  - TOXENV=pypy-dj16
+  - TOXENV=py27-dj14
+  - TOXENV=py27-dj15
+  - TOXENV=py27-dj16
+  - TOXENV=py27-dj17
+  - TOXENV=py27-dj18
+  - TOXENV=py27-dj19
+  - TOXENV=py32-dj15
+  - TOXENV=py32-dj16
+  - TOXENV=py32-dj17
+  - TOXENV=py32-dj18
+  - TOXENV=py32-dj19
+  - TOXENV=py33-dj15
+  - TOXENV=py33-dj16
+  - TOXENV=py33-dj17
+  - TOXENV=py33-dj18
+  - TOXENV=py33-dj19
+  - TOXENV=py34-dj15
+  - TOXENV=py34-dj16
+  - TOXENV=py34-dj17
+  - TOXENV=py34-dj18
+  - TOXENV=py34-dj19
+  - TOXENV=pypy-dj15
+  - TOXENV=pypy-dj16
+  - TOXENV=pypy-dj17
+  - TOXENV=pypy-dj18
+  - TOXENV=pypy-dj19
 install: pip install tox
 script: tox
 branches:

tox.ini

@@ -18,9 +18,13 @@ basepython =
     py34: python3.4
     pypy: pypy
 usedevelop = true
+install_command = echo " {packages} " | tr ' ' '\n' > $TEMP_REQUIREMENTS && pip wheel -r $TEMP_REQUIREMENTS && pip install {opts} -r $TEMP_REQUIREMENTS
 setenv =
     DJANGO_SETTINGS_MODULE = tests.settings.main
     DJANGO_CONFIGURATION = Test
+    PIP_WHEEL_DIR=$HOME/.cache/pip/wheels
+    PIP_FIND_LINKS=file://$HOME/.cache/pip/wheels
+    TEMP_REQUIREMENTS=$TMPDIR/requirements.txt
 deps =
     coverage
     django-discover-runner