Use node v9 to get prebuilt nodegit binaries

Anand Thakker · anandthakker · commit 20ca6c1ddfa3 · 2018-05-10T07:49:31.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,4 +1,4 @@
 language: node_js
 node_js:
-  - "node"
+  - "9"
 cache: yarn
