Refuse to mark completed tasks as complete.

TodoBase.py

@@ -152,12 +152,13 @@ class TodoBase(object):
         Marks the todo as complete.
         Sets the completed flag and sets the completion date to today.
         """
-        self.fields['completed'] = True
-        today = datetime.date.today()
-        self.fields['completionDate'] = today
+        if not self.fields['completed']:
+            self.fields['completed'] = True
+            today = datetime.date.today()
+            self.fields['completionDate'] = today
 
-        self.src = re.sub(r'^(\([A-Z]\) )?', \
-            'x ' + today.isoformat() + ' ', self.src)
+            self.src = re.sub(r'^(\([A-Z]\) )?', \
+                'x ' + today.isoformat() + ' ', self.src)
 
     def __str__(self):
         """ A printer for the todo item. """

test/TodoBaseTest.py

@@ -186,6 +186,12 @@ class TodoBaseTester(unittest.TestCase):
         self.assertEquals(todo.fields['completionDate'], today)
         self.assertTrue(re.match('^x ' + today_str + ' 2014-06-12 Foo', todo.src))
 
+    def test_set_complete5(self):
+        todo = TodoBase.TodoBase("x 2014-06-13 Foo")
+        todo.set_completed()
+
+        self.assertEquals(todo.src, "x 2014-06-13 Foo")
+
     def test_set_text(self):
         todo = TodoBase.TodoBase("(B) Foo")