More Travis tweaking

Author: bachya

.travis.yml

@@ -3,12 +3,19 @@ sudo: false
 matrix:
   fast_finish: true
   include:
-    - python: "3.5.3"
     - python: "3.6"
       after_success: "pipenv run codecov"
     - python: "3.7"
       dist: xenial
       sudo: true
+    - python: "3.8-dev"
+      dist: xenial
+      sudo: true
+      if: branch = dev AND type = push
+  allow_failures:
+    - python: "3.8-dev"
+      dist: xenial
+      sudo: true
 
 cache:
   directories: