Revert "FIX: frozen string exception (#7506)"

Revert “FIX: frozen string exception (#7506)”

This reverts commit c4b7fb2754555bb2b68113897271535e0f9aff58.

diff --git a/app/models/incoming_domain.rb b/app/models/incoming_domain.rb
index 5584689..07fac92 100644
--- a/app/models/incoming_domain.rb
+++ b/app/models/incoming_domain.rb
@@ -24,7 +24,7 @@ class IncomingDomain < ActiveRecord::Base
     url = "http#{https ? "s" : ""}://#{name}"
 
     if https && port != 443 || !https && port != 80
-      url += ":#{port}"
+      url << ":#{port}"
     end
 
     url

GitHub sha: e6cfc584