Fixed #10154: Allow combining F expressions with timedelta values.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15018 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/expressions_regress/models.py

@@ -10,3 +10,16 @@ class Number(models.Model):
     def __unicode__(self):
         return u'%i, %.3f' % (self.integer, self.float)
 
+class Experiment(models.Model):
+    name = models.CharField(max_length=24)
+    assigned = models.DateField()
+    completed = models.DateField()
+    start = models.DateTimeField()
+    end = models.DateTimeField()
+
+    class Meta:
+        ordering = ('name',)
+
+    def duration(self):
+        return self.end - self.start
+