fix confirmation page has broken HTML when a project folding sub project is deleted (#11511)

Contributed by Haruka Yoshihara.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@10083 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/projects/destroy.html.erb

@@ -4,7 +4,8 @@
 <%=l(:text_project_destroy_confirmation)%>
 
 <% if @project_to_destroy.descendants.any? %>
-<br /><%= l(:text_subprojects_destroy_warning, content_tag('strong', h(@project_to_destroy.descendants.collect{|p| p.to_s}.join(', ')))) %>
+<br /><%= l(:text_subprojects_destroy_warning,
+          content_tag('strong', h(@project_to_destroy.descendants.collect{|p| p.to_s}.join(', ')))).html_safe %>
 <% end %>
 </p>
 <p>