[appveyor] fix

Author: nicolas-grekas

.appveyor.yml

@@ -56,7 +56,7 @@ install:
     - php composer.phar self-update
     - copy /Y .composer\* %APPDATA%\Composer\
     - php composer.phar global require --no-progress --no-scripts --no-plugins symfony/flex dev-master
-    - php .github/build-packages.php %APPVEYOR_REPO_COMMIT%^^ src\Symfony\Bridge\PhpUnit
+    - php .github/build-packages.php "HEAD^" src\Symfony\Bridge\PhpUnit
     - IF %APPVEYOR_REPO_BRANCH%==master (SET COMPOSER_ROOT_VERSION=dev-master) ELSE (SET COMPOSER_ROOT_VERSION=%APPVEYOR_REPO_BRANCH%.x-dev)
     - php composer.phar config platform.php 5.3.9
     - php composer.phar update --no-progress --no-suggest --ansi

.github/build-packages.php

@@ -6,15 +6,20 @@
 }
 chdir(dirname(__DIR__));
 
+$json = ltrim(file_get_contents('composer.json'));
+if ($json !== $package = preg_replace('/\n    "repositories": \[\n.*?\n    \],/s', '', $json)) {
+    file_put_contents('composer.json', $package);
+}
+
 $dirs = $_SERVER['argv'];
 array_shift($dirs);
-$mergeBase = trim(shell_exec(sprintf('git merge-base %s HEAD', array_shift($dirs))));
+$mergeBase = trim(shell_exec(sprintf('git merge-base "%s" HEAD', array_shift($dirs))));
 
 $packages = array();
 $flags = \PHP_VERSION_ID >= 50400 ? JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE : 0;
 
 foreach ($dirs as $k => $dir) {
-    if (!system("git diff --name-only \"$mergeBase\" -- $dir", $exitStatus)) {
+    if (!system("git diff --name-only $mergeBase -- $dir", $exitStatus)) {
         if ($exitStatus) {
             exit($exitStatus);
         }
@@ -74,7 +79,6 @@
         'type' => 'composer',
         'url' => 'file://'.str_replace(DIRECTORY_SEPARATOR, '/', dirname(__DIR__)).'/',
     ));
-    $json = preg_replace('/\n    "repositories": \[\n.*?\n    \],/s', '', $json);
     $json = rtrim(json_encode(array('repositories' => $package->repositories), $flags), "\n}").','.substr($json, 1);
     file_put_contents('composer.json', $json);
 }