Merge branch 'improve-ci-example-php-doc' into 'master'

changelogs/unreleased/improve-ci-example-php-doc.yml

+---
+title: Changed composer installer script in the CI PHP example doc
+merge_request: 4342
+author: Jeffrey Cafferata

doc/ci/examples/php.md

@@ -235,7 +235,11 @@ cache:
 
 before_script:
 # Install composer dependencies
-- curl --silent --show-error https://getcomposer.org/installer | php
+- wget https://composer.github.io/installer.sig -O - -q | tr -d '\n' > installer.sig
+- php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
+- php -r "if (hash_file('SHA384', 'composer-setup.php') === file_get_contents('installer.sig')) { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
+- php composer-setup.php
+- php -r "unlink('composer-setup.php'); unlink('installer.sig');"
 - php composer.phar install
 
 ...