Merge pull request #728 from bsipocz/travis_py3.6

Python3.6 needs pytest3 to pass

.travis.yml

@@ -1,7 +1,11 @@
 language: python
 
 python:
+    - 2.7
+    - 3.3
+    - 3.4
     - 3.5
+    - 3.6
 
 # Setting sudo to false opts in to Travis-CI container-based builds.
 sudo: false
@@ -32,14 +36,9 @@ env:
     matrix:
         # Make sure that egg_info works without dependencies
         - SETUP_CMD='egg_info'
-        # Try all python versions with the latest numpy
-        - SETUP_CMD='test'
 
 matrix:
     include:
-        - python: 2.7
-          env: SETUP_CMD='egg_info'
-
         # Do a coverage test in Python 2.
         - python: 2.7
           env: SETUP_CMD='test --coverage'
@@ -58,41 +57,29 @@ matrix:
           env: NUMPY_VERSION=1.9
                CONDA_DEPENDENCIES='cython scipy requests matplotlib h5py beautiful-soup'
 
-        - python: 3.4
-          env: SETUP_CMD='egg_info'
-
         - python: 3.4
           env: NUMPY_VERSION=1.11
                CONDA_DEPENDENCIES='cython scipy requests matplotlib h5py beautiful-soup'
 
         # Try Astropy development version
         - python: 2.7
           env: ASTROPY_VERSION=development
-        - python: 3.5
-          env: ASTROPY_VERSION=development
+        - python: 3.6
+          env: ASTROPY_VERSION=development ASTROPY_USE_SYSTEM_PYTEST=1
 
-        # Try older numpy version, 1.9 is tested above with py3.3
-        - python: 2.7
+        # Try older numpy version, 1.9 is tested above with py3.3 and 1.11 with py3.4
+        - python: 3.5
           env: NUMPY_VERSION=1.10
 
         # Try numpy pre-release version, this runs only when a pre-release
         # is available on pypi.
-        - python: 3.5
-          env: NUMPY_VERSION=prerelease SETUP_CMD='test'
+        - python: 3.6
+          env: NUMPY_VERSION=prerelease SETUP_CMD='test' ASTROPY_USE_SYSTEM_PYTEST=1
 
         # try a version *without* h5py - we need this for readthedocs
         - python: 2.7
           env: CONDA_DEPENDENCIES="`echo $CONDA_DEPENDENCIES | sed 's/ h5py//'`" # this magic incantation removes the substring " h5py" from the dependencies
 
-        - python: 3.6
-          env: SETUP_CMD='test'
-
-    allow_failures:
-        # Python 3.6 currently has a DeprecationWarning related to pytest
-        # that we don't understand at the moment.
-        - python: 3.6
-          env: SETUP_CMD='test'
-
 before_install:
 
     # If there are matplotlib tests, comment these out to