Fix average importance.

Make sure not to make the importance lower than the todos own
importance due to the its parents.

Test case and code were both wrong.

lib/Importance.py

@@ -75,12 +75,17 @@ def importance(p_todo, p_ignore_weekend=False):
     return result if not p_todo.is_completed() else 0
 
 def average_importance(p_todo, p_ignore_weekend=False):
-    sum_importance = importance(p_todo, p_ignore_weekend)
+    own_importance = importance(p_todo, p_ignore_weekend)
+
+    average = 0
     parents = []
 
     if 'parents' in p_todo.attributes:
+        sum_importance = own_importance
         parents = p_todo.attributes['parents']
         for parent in parents:
             sum_importance += importance(parent, p_ignore_weekend)
 
-    return float(sum_importance) / float(1 + len(parents))
+        average = float(sum_importance) / float(1 + len(parents))
+
+    return max(own_importance, average)

test/data/SorterTest11-result.txt

+(A) Important child task p:1 p:2 ((5+4+2)/3=3.67 -> 5)
 (B) Normal task (4)
-(C) Less important child task p:1 p:2 ((3+0+0)/3=1 -> 3)
+(B) Another relatively important task id:2 (4)
 (D) Not-so important parent task id:1 (2)
-(D) Another not-so important task id:2 (2)

test/data/SorterTest11.txt

 (B) Normal task (4)
 (D) Not-so important parent task id:1 (2)
-(D) Another not-so important task id:2 (2)
-(C) Less important child task p:1 p:2 ((3+0+0)/3=1 -> 3)
+(B) Another relatively important task id:2 (4)
+(A) Important child task p:1 p:2 ((5+4+2)/3=3.67 -> 5)