Fix whitespace in selfupdate output, fixes #5980

src/Composer/Command/SelfUpdateCommand.php

@@ -141,7 +141,10 @@ EOT
         $io->write(sprintf("Updating to version <info>%s</info> (%s channel).", $updateVersion, $versionsUtil->getChannel()));
         $remoteFilename = $baseUrl . ($updatingToTag ? "/download/{$updateVersion}/composer.phar" : '/composer.phar');
         $signature = $remoteFilesystem->getContents(self::HOMEPAGE, $remoteFilename.'.sig', false);
+        $io->writeError('   ', false);
         $remoteFilesystem->copy(self::HOMEPAGE, $remoteFilename, $tempFilename, !$input->getOption('no-progress'));
+        $io->writeError('');
+
         if (!file_exists($tempFilename) || !$signature) {
             $io->writeError('<error>The download of the new composer version failed for an unexpected reason</error>');