partial locals do not accept a string constant

When I try to set a locals variable to a string in a partial render, it doesn't get assigned properly. If I instead use an intermediate variable, it works.

View file: <%= render :partial => 'partial', :locals => {:who => 'me'} %>

Partial file: <%= @who %>

Result: empty string

Expected result: 'me'

Work-around view file: <% @who => 'me' %><%= render :partial => 'partial', :locals => {:who => @who} %>

The ActionView::Partials docs don't mention that the targets have to be variables, but that appears to be the case.

The ActionController::Base docs show an example using a string: render :partial => "person", :locals => { :name => "david" }