Lock Travis distro so new future defaults will not break the build

clue · clue · commit 324aae00291c · 2017-08-04T16:03:30.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -9,6 +9,9 @@ php:
   - 7.1
   - nightly
 
+# lock distro so new future defaults will not break the build
+dist: precise
+
 # also test against HHVM, but require "trusty" and ignore errors
 matrix:
   include:
