Make sure a version not found issue is reported as such for clarity, fixes #9500

src/Composer/Command/SelfUpdateCommand.php

@@ -21,6 +21,7 @@ use Composer\SelfUpdate\Keys;
 use Composer\SelfUpdate\Versions;
 use Composer\IO\IOInterface;
 use Composer\Downloader\FilesystemException;
+use Composer\Downloader\TransportException;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Input\InputArgument;
@@ -211,7 +212,13 @@ EOT
 
         $io->write(sprintf("Upgrading to version <info>%s</info> (%s channel).", $updateVersion, $channelString));
         $remoteFilename = $baseUrl . ($updatingToTag ? "/download/{$updateVersion}/composer.phar" : '/composer.phar');
-        $signature = $httpDownloader->get($remoteFilename.'.sig')->getBody();
+        try {
+            $signature = $httpDownloader->get($remoteFilename.'.sig')->getBody();
+        } catch (TransportException $e) {
+            if ($e->getStatusCode() === 404) {
+                throw new \InvalidArgumentException('Version "'.$updateVersion.'" could not be found.', 0, $e);
+            }
+        }
         $io->writeError('   ', false);
         $httpDownloader->copy($remoteFilename, $tempFilename);
         $io->writeError('');

src/Composer/Compiler.php

@@ -110,7 +110,7 @@ class Compiler
         $finder = new Finder();
         $finder->files()
             ->ignoreVCS(true)
-            ->notPath('/\/(composer\.(json|lock)|[A-Z]+\.md|\.gitignore|phpunit\.xml\.dist|phpstan\.neon\.dist|phpstan-config\.neon)$/')
+            ->notPath('/\/(composer\.(json|lock)|[A-Z]+\.md|\.gitignore|appveyor.yml|phpunit\.xml\.dist|phpstan\.neon\.dist|phpstan-config\.neon)$/')
             ->notPath('/bin\/(jsonlint|validate-json|simple-phpunit)(\.bat)?$/')
             ->notPath('symfony/debug/Resources/ext/')
             ->notPath('justinrainbow/json-schema/demo/')