Check page.nil? before page.wiki (#1535)

test/test_app.rb

@@ -647,6 +647,14 @@ EOF
     assert_match /meta name="robots" content="noindex, nofollow"/, last_response.body
   end
 
+  test 'history/NO-EXIST redirects to Home' do
+    get '/gollum/history/NO-EXIST'
+    follow_redirect!
+    assert_equal last_request.fullpath, '/'
+    # redirect again from / to /Home
+    assert_equal last_response.status, 302
+  end
+
   def app
     Precious::App
   end