don't use url but path for form action

URLs are potentially broken (wrong scheme).

app/views/users/_available_global_roles.html.erb

@@ -25,7 +25,7 @@ end%>
 <div class="splitcontentright" id="available_principal_roles">
 <fieldset><legend><%= Role.model_name.human(:count => 2) %></legend>
 <span id="additional_principal_roles">
-<%= form_for(:principal_roles, :url => principal_roles_url, :method => :post, :remote => :true) do %>
+<%= form_for(:principal_roles, :url => principal_roles_path, :method => :post, :remote => :true) do %>
 	<%= hidden_field_tag 'principal_role[principal_id]', user.id %>
 <% available_additional_global_roles(global_roles, user).each do |role| %>
   <%= render :partial => 'users/available_global_role', :locals => {:role => role} %>

spec/views/users/_available_global_roles.html.erb_spec.rb

@@ -0,0 +1,41 @@
+#-- copyright
+# OpenProject is a project management system.
+# Copyright (C) 2012-2014 the OpenProject Foundation (OPF)
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See doc/COPYRIGHT.rdoc for more details.
+#++
+
+require 'spec_helper'
+
+describe 'users/_available_global_roles' do
+  let(:user)         { FactoryGirl.create :user }
+  let(:global_roles) { FactoryGirl.create_list :global_role, 3 }
+
+  it 'links to the principal roles controller using a path, not a URL' do
+    render :partial => "users/available_global_roles", :locals => {:user => user, :global_roles => global_roles}
+
+    expect(response.body).to match /\/principal_roles/
+    expect(response.body).not_to match /http(s)?/
+  end
+end