Respect disable-tls in Versions::getLatest

Use http to get the latest version when disable-tls is true and error-
trap DiagnoseCommand::checkVersion so that all checks can complete.
Fixes #8657.

src/Composer/Command/DiagnoseCommand.php

@@ -432,7 +432,11 @@ EOT
         }
 
         $versionsUtil = new Versions($config, $this->rfs);
-        $latest = $versionsUtil->getLatest();
+        try {
+            $latest = $versionsUtil->getLatest();
+        } catch (\Exception $e) {
+            return $e;
+        }
 
         if (Composer::VERSION !== $latest['version'] && Composer::VERSION !== '@package_version@') {
             return '<comment>You are not running the latest '.$versionsUtil->getChannel().' version, run `composer self-update` to update ('.Composer::VERSION.' => '.$latest['version'].')</comment>';

src/Composer/SelfUpdate/Versions.php

@@ -63,7 +63,12 @@ class Versions
 
     public function getLatest($channel = null)
     {
-        $protocol = extension_loaded('openssl') ? 'https' : 'http';
+        if ($this->config->get('disable-tls') === true) {
+            $protocol = 'http';
+        } else {
+            $protocol = 'https';
+        }
+
         $versions = JsonFile::parseJson($this->rfs->getContents('getcomposer.org', $protocol . '://getcomposer.org/versions', false));
 
         foreach ($versions[$channel ?: $this->getChannel()] as $version) {