Allow failures on nightly due to 'Internal error: encountered unexpected error in runtime'

Author: tkoolen

.travis.yml

@@ -15,11 +15,9 @@ notifications:
 git:
   depth: 99999999
 
-## uncomment the following lines to allow failures on nightly julia
-## (tests will run but not make your overall status red)
-#matrix:
-#  allow_failures:
-#  - julia: nightly
+matrix:
+  allow_failures:
+    - julia: nightly
 
 ## uncomment and modify the following lines to manually install system packages
 #addons: