Travis: Don't install npm@5 when the current npm is newer.

diff --git a/.travis.yml b/.travis.yml
index d4a73d02647cab7cee12a69da0af780e4702e645..85ad14526e3ae7fa0fd08430bf1a9689ee2dc316 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,7 +9,7 @@ node_js:
   - "6"
   - "8"
 before_install:
-  - if [[ `npm -v` != 5* ]]; then npm install -g npm@5; fi
+  - if [[ $(npm -v | cut -d. -f1) -lt "5" ]]; then npm install -g npm@5; fi
 install:
   - bundle install --deployment --jobs=3 --retry=3
   - npm install