Travis: fix the latest breakage - use group:

See https://blog.travis-ci.com/2017-08-29-trusty-image-updates
2017-09-08 13:02:07 +01:00 · 2017-09-08 13:02:07 +01:00 · 42a6dd00d8
parent e12f116ec1
commit 42a6dd00d8
1 changed files with 1 additions and 1 deletions
--- a/.travis.yml
+++ b/.travis.yml
@ -1,6 +1,6 @@
 python:
  - "2.7"
-
+group: deprecated-2017Q3
 script:
  - mkdir BUILD
 # Assert that the Doxygen build produced no warnings.