Fix parse error in travis' shell script.

.travis.yml

@@ -75,7 +75,7 @@ script:
   - if [[ $DEFAULT = 1 && $TRAVIS_PHP_VERSION = 7.* ]]; then export CODECOVERAGE=1 ; phpdbg -qrr vendor/bin/phpunit --coverage-clover=clover.xml; fi
   - if [[ $DEFAULT = 1 && $TRAVIS_PHP_VERSION != 7.* ]]; then vendor/bin/phpunit; fi
 
-  - if [ $PHPCS = 1 ]; then vendor/bin/phpcs -p --extensions=php --standard=vendor/cakephp/cakephp-codesniffer/CakePHP ./src ./tests; fi
+  - if [[ $PHPCS = 1 ]]; then vendor/bin/phpcs -p --extensions=php --standard=vendor/cakephp/cakephp-codesniffer/CakePHP ./src ./tests; fi
 
 after_success:
   - if [[ $DEFAULT = 1 && $TRAVIS_PHP_VERSION = 7.* ]]; then bash <(curl -s https://codecov.io/bash); fi