Run HHVM against Guzzle 6 instead of 5

Author: ddeboer

.travis.yml

@@ -22,8 +22,8 @@ branches:
     - '/^\d+\.\d+$/'
 
 install:
-  - if [[ "$TRAVIS_PHP_VERSION" == "5.4" || "$TRAVIS_PHP_VERSION" == "hhvm" ]]; then composer remove "php-http/guzzle6-adapter" --dev --no-update; fi
-  - if [[ "$TRAVIS_PHP_VERSION" == "5.4" || "$TRAVIS_PHP_VERSION" == "hhvm" ]]; then composer require "php-http/guzzle5-adapter" --dev --no-update; fi
+  - if [[ "$TRAVIS_PHP_VERSION" == "5.4" ]]; then composer remove "php-http/guzzle6-adapter" --dev --no-update; fi
+  - if [[ "$TRAVIS_PHP_VERSION" == "5.4" ]]; then composer require "php-http/guzzle5-adapter" --dev --no-update; fi
   - composer update $COMPOSER_FLAGS --prefer-source --no-interaction
 
 before_script: