Test on 1.18.0 as well

jhecking · jhecking · commit fd745c226779 · 2018-01-25T11:06:31.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ rust:
   - nightly
   - beta
   - stable
+  - 1.18.0
 matrix:
   allow_failures:
     - rust: nightly
