Merge pull request #1509 from xrstf/quiet-xcopy

do not output the xcopy summary

src/Composer/Util/Filesystem.php

@@ -159,7 +159,7 @@ class Filesystem
         if (defined('PHP_WINDOWS_VERSION_BUILD')) {
             // Try to copy & delete - this is a workaround for random "Access denied" errors.
             $command = sprintf('xcopy %s %s /E /I /Q', escapeshellarg($source), escapeshellarg($target));
-            if (0 === $this->processExecutor->execute($command)) {
+            if (0 === $this->processExecutor->execute($command, $output)) {
                 $this->remove($source);
 
                 return;