Make composer setup on Travis work on PHP 5.2.

Author: Felix Arntz

.travis.yml

@@ -52,18 +52,26 @@ before_script:
     case "$TRAVIS_PHP_VERSION" in
       5.6|5.5|5.4|5.3)
         composer global require "phpunit/phpunit:^4"
-        composer install
         ;;
       5.2)
         ;;
       *)
         composer global require "phpunit/phpunit:^6"
-        composer install
         ;;
     esac
-  - cd php52
-  - composer install
-  - cd ..
+  - |
+    if [[ "$TRAVIS_PHP_VERSION" == "5.2" ]]; then
+      phpenv global 5.3
+      cd php52
+      composer install
+      cd ..
+      phpenv global "$TRAVIS_PHP_VERSION"
+    else
+      composer install
+      cd php52
+      composer install
+      cd ..
+    fi
   - PLUGIN_SLUG=$(basename $(pwd))
   - export WP_DEVELOP_DIR=/tmp/wordpress/
   - git clone --depth=50 --branch="$WP_VERSION" git://develop.git.wordpress.org/ /tmp/wordpress