Fix create-project regression when using path repos with relative paths, fixes #12150

src/Composer/Command/CreateProjectCommand.php

@@ -424,21 +424,16 @@ EOT
             throw new \InvalidArgumentException($errorMessage .'.');
         }
 
-        $oldCwd = Platform::getCwd();
         // handler Ctrl+C aborts gracefully
         @mkdir($directory, 0777, true);
         if (false !== ($realDir = realpath($directory))) {
-            $signalHandler = SignalHandler::create([SignalHandler::SIGINT, SignalHandler::SIGTERM, SignalHandler::SIGHUP], function (string $signal, SignalHandler $handler) use ($realDir, $oldCwd) {
+            $signalHandler = SignalHandler::create([SignalHandler::SIGINT, SignalHandler::SIGTERM, SignalHandler::SIGHUP], function (string $signal, SignalHandler $handler) use ($realDir) {
-                chdir($oldCwd);
                 $this->getIO()->writeError('Received '.$signal.', aborting', true, IOInterface::DEBUG);
                 $fs = new Filesystem();
                 $fs->removeDirectory($realDir);
                 $handler->exitWithLastSignal();
             });
         }
-        if (!chdir($directory)) {
-            throw new \RuntimeException('Failed to chdir into the new project dir at '.$directory);
-        }
 
         // avoid displaying 9999999-dev as version if default-branch was selected
         if ($package instanceof AliasPackage && $package->getPrettyVersion() === VersionParser::DEFAULT_BRANCH_ALIAS) {
@@ -472,6 +467,7 @@ EOT
         $installedFromVcs = 'source' === $package->getInstallationSource();
 
         $io->writeError('<info>Created project in ' . $directory . '</info>');
+        chdir($directory);
 
         // ensure that the env var being set does not interfere with create-project
         // as it is probably not meant to be used here, so we do not use it if a composer.json can be found

src/Composer/Downloader/FileDownloader.php

@@ -350,7 +350,14 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
             $this->io->writeError("  - " . InstallOperation::format($package));
         }
 
-        $this->filesystem->emptyDirectory($path);
+        $vendorDir = $this->config->get('vendor-dir');
+
+        // clean up the target directory, unless it contains the vendor dir, as the vendor dir contains
+        // the file to be installed. This is the case when installing with create-project in the current directory
+        // but in that case we ensure the directory is empty already in ProjectInstaller so no need to empty it here.
+        if (false === strpos($this->filesystem->normalizePath($vendorDir), $this->filesystem->normalizePath($path.DIRECTORY_SEPARATOR))) {
+            $this->filesystem->emptyDirectory($path);
+        }
         $this->filesystem->ensureDirectoryExists($path);
         $this->filesystem->rename($this->getFileName($package, $path), $path . '/' . $this->getDistPath($package, PATHINFO_BASENAME));