Use _instance_or_null in github3.git

sigmavirus24 · sigmavirus24 · commit 293a2c5a691f · 2014-11-10T20:08:47.000-06:00
diff --git a/github3/git.py b/github3/git.py
@@ -213,7 +213,7 @@ def recurse(self):
         """
         json = self._json(self._get(self._api, params={'recursive': '1'}),
                           200)
-        return Tree(json, self) if json else None
+        return self._instance_or_null(Tree, json)
 
 
 class Hash(GitHubObject):
