diff -up ./bin/composer.rpm ./bin/composer
--- ./bin/composer.rpm	2020-10-25 06:23:06.000000000 +0100
+++ ./bin/composer	2020-10-25 06:23:12.862707931 +0100
@@ -6,7 +6,7 @@ if (PHP_SAPI !== 'cli' && PHP_SAPI !== '
 }
 
 setlocale(LC_ALL, 'C');
-require __DIR__.'/../src/bootstrap.php';
+require '/usr/share/php/Composer/autoload.php';
 
 use Composer\Console\Application;
 use Composer\XdebugHandler\XdebugHandler;
diff -up ./src/Composer/Autoload/AutoloadGenerator.php.rpm ./src/Composer/Autoload/AutoloadGenerator.php
--- ./src/Composer/Autoload/AutoloadGenerator.php.rpm	2020-10-25 06:23:06.000000000 +0100
+++ ./src/Composer/Autoload/AutoloadGenerator.php	2020-10-25 06:23:12.863707931 +0100
@@ -364,7 +364,7 @@ EOF;
         $filesystem->filePutContentsIfModified($targetDir.'/autoload_real.php', $this->getAutoloadRealFile(true, (bool) $includePathFileContents, $targetDirLoader, (bool) $includeFilesFileContents, $vendorPathCode, $appBaseDirCode, $suffix, $useGlobalIncludePath, $prependAutoloader, $staticPhpVersion, $checkPlatform));
 
         $filesystem->safeCopy(__DIR__.'/ClassLoader.php', $targetDir.'/ClassLoader.php');
-        $filesystem->safeCopy(__DIR__.'/../../../LICENSE', $targetDir.'/LICENSE');
+        $filesystem->safeCopy((getenv('BUILDROOT')?:'') . '/usr/share/composer/LICENSE', $targetDir.'/LICENSE');
 
         if ($this->runScripts) {
             $this->eventDispatcher->dispatchScript(ScriptEvents::POST_AUTOLOAD_DUMP, $this->devMode, array(), array(
diff -up ./src/Composer/Compiler.php.rpm ./src/Composer/Compiler.php
--- ./src/Composer/Compiler.php.rpm	2020-10-25 06:23:12.863707931 +0100
+++ ./src/Composer/Compiler.php	2020-10-25 06:26:14.912591239 +0100
@@ -99,7 +99,7 @@ class Compiler
         // Add Composer resources
         $finder = new Finder();
         $finder->files()
-            ->in(__DIR__.'/../../res')
+            ->in((getenv('BUILDROOT')?:'') . '/usr/share/composer/res')
             ->sort($finderSort)
         ;
         foreach ($finder as $file) {
diff -up ./src/Composer/Json/JsonFile.php.rpm ./src/Composer/Json/JsonFile.php
--- ./src/Composer/Json/JsonFile.php.rpm	2020-10-25 06:23:06.000000000 +0100
+++ ./src/Composer/Json/JsonFile.php	2020-10-25 06:23:12.863707931 +0100
@@ -34,7 +34,7 @@ class JsonFile
     const JSON_PRETTY_PRINT = 128;
     const JSON_UNESCAPED_UNICODE = 256;
 
-    const COMPOSER_SCHEMA_PATH = '/../../../res/composer-schema.json';
+    const COMPOSER_SCHEMA_PATH = '/usr/share/composer/res/composer-schema.json';
 
     private $path;
     private $httpDownloader;
@@ -179,7 +179,7 @@ class JsonFile
         }
 
         if (null === $schemaFile) {
-            $schemaFile = __DIR__ . self::COMPOSER_SCHEMA_PATH;
+            $schemaFile = (getenv('BUILDROOT')?:'') . self::COMPOSER_SCHEMA_PATH;
         }
 
         // Prepend with file:// only when not using a special schema already (e.g. in the phar)
diff -up ./tests/Composer/Test/Json/ComposerSchemaTest.php.rpm ./tests/Composer/Test/Json/ComposerSchemaTest.php
--- ./tests/Composer/Test/Json/ComposerSchemaTest.php.rpm	2020-10-25 06:23:06.000000000 +0100
+++ ./tests/Composer/Test/Json/ComposerSchemaTest.php	2020-10-25 06:23:12.863707931 +0100
@@ -113,7 +113,8 @@ class ComposerSchemaTest extends TestCas
     private function check($json)
     {
         $validator = new Validator();
-        $validator->check(json_decode($json), (object) array('$ref' => 'file://' . __DIR__ . '/../../../../res/composer-schema.json'));
+        $f = (getenv('BUILDROOT')?:'') . '/usr/share/composer/res/composer-schema.json';
+        $validator->check(json_decode($json), (object) array('$ref' => 'file://' . $f));
 
         if (!$validator->isValid()) {
             $errors = $validator->getErrors();
diff -up ./tests/Composer/Test/PolyfillTestCase.php.rpm ./tests/Composer/Test/PolyfillTestCase.php
--- ./tests/Composer/Test/PolyfillTestCase.php.rpm	2020-10-25 06:23:06.000000000 +0100
+++ ./tests/Composer/Test/PolyfillTestCase.php	2020-10-25 06:23:12.863707931 +0100
@@ -18,8 +18,33 @@ namespace Composer\Test {
     use PHPUnit\Framework\Constraint\StringContains;
     use PHPUnit\Framework\Constraint\TraversableContains;
 
-    if (method_exists('PHPUnit\Framework\TestCase', 'assertStringContainsString')) {
+    if (method_exists('PHPUnit\Framework\TestCase', 'assertFileDoesNotExist')) {
         abstract class PolyfillTestCase extends TestCase {}
+    } else if (method_exists('PHPUnit\Framework\TestCase', 'assertStringContainsString')) {
+        abstract class PolyfillTestCase extends TestCase {
+            /**
+             * @param string $filename
+             * @param string $message
+             *
+             * @return void
+             */
+            public static function assertFileDoesNotExist($filename, $message = '')
+            {
+                static::assertFileNotExists($filename, $message);
+            }
+
+            /**
+             * @param string $pattern
+             * @param string $string
+             * @param string $message
+             *
+             * @return void
+             */
+            public static function assertMatchesRegularExpression($pattern, $string, $message = '')
+            {
+                static::assertRegExp($pattern, $string, $message);
+            }
+        }
     } else {
         abstract class PolyfillTestCase extends TestCase
         {