Overactive block helper deprecation warning when iterating on an ActiveModel::Errors object

During the switch over from <% style block helpers to <%= style something appears to have gone awry.

In the following ERB, the flash.each_pair line does not generate a deprecation warning, however the messages.each_pair line does.

    <% flash.each_pair do |flash_type, messages| %>
      <ul class="<% flash_type %> flash">
        <% messages.each do |_, message| %>
          <li><%= message %></li>
        <% end %>
      </ul>
    <% end %>

At this point, flash is (I assume) a standard hash, at least whatever Rails provides, whereas messages is an ActiveModel::Errors object.

Since ActiveModel::Errors#each yields, it's correct to use the old-style block notation. Any return value is undefined (and its output unwanted). Unfortunately, Rails emits a deprecation warning for this object.

This behaviour is identical for ERB and Haml.

Regards,
Elliot Crosby-McCullough