Opt into Trusty builds. (pytorch#2214)

* Opt into Trusty builds. Signed-off-by: Edward Z. Yang <ezyang@fb.com> * Bump to 2.7.9. Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Author: ezyang

.travis.yml

@@ -1,7 +1,8 @@
 # https://travis-ci.org/pytorch/pytorch
 language: python
+dist: trusty
 python:
- - 2.7.8
+ - 2.7.9
  - 2.7
  - 3.5
  - 3.6