src/Composer/Util/Filesystem.php
public function unlink($path)
    {
        $unlinked = @$this->unlinkImplementation($path);
        if (!$unlinked) {
            // retry after a bit on windows since it tends to be touchy with mass removals
            if (Platform::isWindows()) {
                usleep(350000);
                $unlinked = @$this->unlinkImplementation($path);
            }
            
            if (!$unlinked) {
                $error = error_get_last();
                $message = 'Could not delete '.$path.': ' . @$error['message'];
                if (Platform::isWindows()) {
                    $message .= "\nThis can be due to an antivirus or the Windows Search Indexer locking the file while they are analyzed";
                }

                throw new \RuntimeException($message);
            }
        }

        return true;
    }
public function unlink($path)
    {
        $unlinked = @$this->unlinkImplementation($path);
        if (!$unlinked) {
            // retry after a bit on windows since it tends to be touchy with mass removals
            if (Platform::isWindows()) {
                usleep(350000);
                $unlinked = @$this->unlinkImplementation($path);
            }
            
            if (!$unlinked) {
                $error = error_get_last();
                $message = 'Could not delete '.$path.': ' . @$error['message'];
                if (Platform::isWindows()) {
                    $message .= "\nThis can be due to an antivirus or the Windows Search Indexer locking the file while they are analyzed";
                }

                throw new \RuntimeException($message);
            }
        }

        return true;
    }
Attempts to unlink a file and in case of failure retries after 350ms on windows

@param  string            $path
@throws \RuntimeException
@return bool