Check view policy, not join policy, when raising an error for Phame custom domains

Summary: A user in IRC hit this; this looks like a typo.

Test Plan: Created a new blog with a public view policy, a non-public join policy, and a custom domain.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: legien, epriestley

Differential Revision: https://secure.phabricator.com/D8980

src/applications/phame/controller/blog/PhameBlogEditController.php

@@ -74,7 +74,7 @@ final class PhameBlogEditController
           $errors[] = $error_text;
           $e_custom_domain = $error_label;
         }
-        if ($blog->getJoinPolicy() != PhabricatorPolicies::POLICY_PUBLIC) {
+        if ($blog->getViewPolicy() != PhabricatorPolicies::POLICY_PUBLIC) {
           $errors[] = pht(
             'For custom domains to work, the blog must have a view policy of '.
             'public.');