better colors for barcharts

util/stats/barchart.py:
    If there are fewer than 5 colors, pick from a subset of
    5 so there is more consistency in colors between graphs

--HG--
extra : convert_revision : 6cf64c2f8ed81e714e24a3ebe5a7a60ca168b231

util/stats/barchart.py

@@ -47,7 +47,10 @@ class BarChart(ChartOptions):
         cmap = matplotlib.cm.get_cmap(self.colormap)
         if count == 1:
             return cmap([ 0.5 ])
-        else:
+
+        if count < 5:
+            return cmap(arange(5) / float(4))[:count]
+
         return cmap(arange(count) / float(count - 1))
 
     # The input data format does not match the data format that the