/usr/share/php/Composer/Downloader/ is in composer 1.0.0~beta2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Composer/Downloader/ArchiveDownloader.php
/usr/share/php/Composer/Downloader/ChangeReportInterface.php
/usr/share/php/Composer/Downloader/DownloadManager.php
/usr/share/php/Composer/Downloader/DownloaderInterface.php
/usr/share/php/Composer/Downloader/DvcsDownloaderInterface.php
/usr/share/php/Composer/Downloader/FileDownloader.php
/usr/share/php/Composer/Downloader/FilesystemException.php
/usr/share/php/Composer/Downloader/GitDownloader.php
/usr/share/php/Composer/Downloader/GzipDownloader.php
/usr/share/php/Composer/Downloader/HgDownloader.php
/usr/share/php/Composer/Downloader/PathDownloader.php
/usr/share/php/Composer/Downloader/PearPackageExtractor.php
/usr/share/php/Composer/Downloader/PerforceDownloader.php
/usr/share/php/Composer/Downloader/PharDownloader.php
/usr/share/php/Composer/Downloader/RarDownloader.php
/usr/share/php/Composer/Downloader/SvnDownloader.php
/usr/share/php/Composer/Downloader/TarDownloader.php
/usr/share/php/Composer/Downloader/TransportException.php
/usr/share/php/Composer/Downloader/VcsDownloader.php
/usr/share/php/Composer/Downloader/XzDownloader.php
/usr/share/php/Composer/Downloader/ZipDownloader.php