[ci] use deprecated trusty build for now
diff --git a/.travis.yml b/.travis.yml
index 8f2febd..9f37374 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,6 @@
 language: python
 dist: trusty
+group: deprecated-2017Q2
 
 python:
   - "2.7"