Fix for undefined method `+' for :percentage_uncovered:Symbol (NoMethodError)

When I run rcov using following settings in .metrics file in my rails root it gives following error 

MetricFu::Configuration.run do |config|  
  config.configure_metric(:rcov) do |rcov|
    rcov.activate
    rcov.enabled = true
    rcov.external = File.expand_path("coverage/rcov/rcov.txt", Dir.pwd)
  end
end



/home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/scoring_strategies.rb:18:in `each': undefined method `+' for :percentage_uncovered:Symbol (NoMethodError)
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/scoring_strategies.rb:18:in `inject'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/scoring_strategies.rb:18:in `sum'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/scoring_strategies.rb:22:in `average'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/hotspot.rb:42:in `reduce'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:61:in `block in calculate_metric_scores'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:60:in `calculate_metric_scores'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:41:in `calculate_score_for_granularity'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:36:in `block in calculate_scores_by_granularities'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:35:in `each'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:35:in `calculate_scores_by_granularities'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:13:in `block in calculate_scores'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:12:in `each'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/analysis/rankings.rb:12:in `calculate_scores'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/hotspot_analyzer.rb:53:in `setup'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/hotspot_analyzer.rb:21:in `initialize'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/hotspots.rb:19:in `new'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/hotspots/hotspots.rb:19:in `analyze'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/generator.rb:100:in `block in generate_result'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/generator.rb:98:in `each'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/metrics/generator.rb:98:in `generate_result'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/reporting/result.rb:46:in `add'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/run.rb:21:in `block in measure'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/run.rb:19:in `each'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/run.rb:19:in `measure'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/run.rb:10:in `run'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/cli/helper.rb:11:in `run'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/lib/metric_fu/cli/client.rb:18:in `run'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/gems/metric_fu-4.4.3/bin/metric_fu:9:in `<top (required)>'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/bin/metric_fu:23:in `load'
	from /home/xpanxion/.rvm/gems/ruby-1.9.2-p320/bin/metric_fu:23:in `<main>'