Rescue database error in application settings if the database still doesn't exist.

lib/gitlab/current_settings.rb

@@ -8,7 +8,7 @@ module Gitlab
         else
           fake_application_settings
         end
-      rescue ActiveRecord::NoDatabaseError
+      rescue ActiveRecord::NoDatabaseError, database_adapter.constantize::Error
         fake_application_settings
       end
     end
@@ -22,5 +22,16 @@ module Gitlab
         sign_in_text: Settings.extra['sign_in_text'],
       )
     end
+
+    # We need to check which database is setup
+    # but we cannot assume that the database exists already.
+    # Not checking this will break "rake gitlab:setup".
+    def database_adapter
+      if Rails.configuration.database_configuration[Rails.env]['adapter'] == 'mysql2'
+        "Mysql2"
+      else
+        "PG"
+      end
+    end
   end
 end