Rollup merge of rust-lang#46694 - kennytm:temporarily-use-old-travis-image, r=aidanhs

kennytm · web-flow · commit 80d1de97ade0 · 2017-12-13T04:28:09.000+08:00
Temporarily use the old Travis image. Use it until travis-ci/travis-ci#8891 is fixed. (See also https://blog.travis-ci.com/2017-12-12-new-trusty-images-q4-launch) r? @aidanhs
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,7 @@
 language: shell
 sudo: required
 dist: trusty
+group: deprecated-2017Q4
 services:
   - docker
 
