build: fix running Node.js 0.8 tests on Travis CI

Author: dougwilson

.travis.yml

@@ -13,7 +13,7 @@ before_install:
   - "test $TRAVIS_NODE_VERSION != '0.8' || npm rm --save-dev istanbul"
 script:
   # Run test script, depending on istanbul install
-  - "test -n $(npm -ps ls istanbul) || npm test"
-  - "test -z $(npm -ps ls istanbul) || npm run-script test-travis"
+  - "test ! -z $(npm -ps ls istanbul) || npm test"
+  - "test   -z $(npm -ps ls istanbul) || npm run-script test-travis"
 after_script:
   - "test -e ./coverage/lcov.info && npm install coveralls@2 && cat ./coverage/lcov.info | coveralls"