Fixed: error when previewing a new wiki page (#1292) introduced in r1415.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1445 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/wiki_controller.rb

@@ -162,7 +162,8 @@ class WikiController < ApplicationController
   
   def preview
     page = @wiki.find_page(params[:page])
-    return render_403 unless editable?(page)
+    # page is nil when previewing a new page
+    return render_403 unless page.nil? || editable?(page)
     @attachements = page.attachments if page
     @text = params[:content][:text]
     render :partial => 'common/preview'