From fdc25777daeeda8acb6d5196ed07c6b2fb23a896 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sun, 3 Jul 2016 12:19:01 +0800
Subject: [PATCH] master/dataset_db: support keeping old persist flag

---
 artiq/master/databases.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/artiq/master/databases.py b/artiq/master/databases.py
index 5e2c7d004..9ad0c1be3 100644
--- a/artiq/master/databases.py
+++ b/artiq/master/databases.py
@@ -57,7 +57,12 @@ class DatasetDB(TaskObject):
         process_mod(self.data, mod)
 
     # convenience functions (update() can be used instead)
-    def set(self, key, value, persist=False):
+    def set(self, key, value, persist=None):
+        if persist is None:
+            if key in self.data.read:
+                persist = self.data.read[key][0]
+            else:
+                persist = False
         self.data[key] = (persist, value)
 
     def delete(self, key):