Add HHVM support in UA header

src/Composer/Util/RemoteFilesystem.php

@@ -385,15 +385,19 @@ class RemoteFilesystem
 
     protected function getOptionsForUrl($originUrl, $additionalOptions)
     {
+        if (defined('HHVM_VERSION')) {
+            $phpVersion = 'HHVM ' . HHVM_VERSION;
+        } else {
+            $phpVersion = 'PHP ' . PHP_MAJOR_VERSION . '.' . PHP_MINOR_VERSION . '.' . PHP_RELEASE_VERSION;
+        }
+
         $headers = array(
             sprintf(
-                'User-Agent: Composer/%s (%s; %s; PHP %s.%s.%s)',
+                'User-Agent: Composer/%s (%s; %s; %s)',
                 Composer::VERSION === '@package_version@' ? 'source' : Composer::VERSION,
                 php_uname('s'),
                 php_uname('r'),
-                PHP_MAJOR_VERSION,
-                PHP_MINOR_VERSION,
-                PHP_RELEASE_VERSION
+                $phpVersion
             )
         );