[DIFF] show empty character when null value is expected by generator

lib/refrepo/gen/oar-properties.rb

@@ -958,8 +958,12 @@ def do_diff(options, generated_hierarchy, refrepo_properties)
 
               {:cpu => "cpu", :core => "core", :cpuset => "cpuset", :gpu => "gpu", :gpudevice => "gpudevice"}.each do |key, value|
                 if row[key].to_s != corresponding_resource[0][value].to_s and not (key == :gpu and row[key].nil? and corresponding_resource[0][value] == 0)
+                  expected_value = row[key]
+                  if expected_value == ""
+                    expected_value = "ø"
+                  end
                   fix_cmd = <<-TXT
-# Error: Resource #{resc["id"]} (host=#{resc["network_address"]} cpu=#{resc["cpu"]} core=#{resc["core"]} cpuset=#{resc["cpuset"]} gpu=#{resc["gpu"]} gpudevice=#{resc["gpudevice"]}) has a mismatch for ressource #{value.upcase}: API gives #{resc[value]}, generator wants #{row[key]}.
+# Error: Resource #{resc["id"]} (host=#{resc["network_address"]} cpu=#{resc["cpu"]} core=#{resc["core"]} cpuset=#{resc["cpuset"]} gpu=#{resc["gpu"]} gpudevice=#{resc["gpudevice"]}) has a mismatch for ressource #{value.upcase}: OAR API gives #{resc[value]}, generator wants #{expected_value}.
 TXT
                   fix_cmds += "#{fix_cmd}"
                 end