Fix: Changing the tracker to a tracker with the tracker field set to read-only won't work (#27110)

Patch by Felix Schäfer.


git-svn-id: http://svn.redmine.org/redmine/trunk@17032 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/issues/_form.html.erb

@@ -14,7 +14,7 @@
                 :onchange => "updateIssueFrom('#{escape_javascript update_issue_form_path(@project, @issue)}', this)" %></p>
 <% end %>
 
-<% if @issue.safe_attribute? 'tracker_id' %>
+<% if @issue.safe_attribute?('tracker_id') || (@issue.persisted? && @issue.tracker_id_changed?) %>
 <p><%= f.select :tracker_id, trackers_options_for_select(@issue), {:required => true},
                 :onchange => "updateIssueFrom('#{escape_javascript update_issue_form_path(@project, @issue)}', this)" %></p>
 <% end %>