Run tests against Python 3.7, rather than nightly

Author: stasm

.travis.yml

@@ -1,10 +1,14 @@
-sudo: false
 language: python
 python:
-  - "2.7"
-  - "3.5"
-  - "3.6"
-  - "nightly"
+  - 2.7
+  - 3.5
+  - 3.6
+# XXX https://github.com/travis-ci/travis-ci/issues/9815#issuecomment-411073985
+matrix:
+  include:
+    - python: 3.7
+      dist: xenial
+      sudo: true
 install: pip install tox-travis
 script: tox
 notifications:

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, py35, py36
+envlist = py27, py35, py36, py37
 skipsdist=True
 
 [testenv]