1 files changed, 17 insertions, 10 deletions
diff --git a/Mailman/MailList.py b/Mailman/MailList.py
index 69fb500a9..6c9c7fb20 100644
--- a/Mailman/MailList.py
+++ b/Mailman/MailList.py
@@ -535,18 +535,25 @@ class MailList(MailCommandHandler, HTMLFormatter, Deliverer, ListAdmin,
     # Sanity checks
     #
     def CheckVersion(self, stored_state):
-        """Migrate prior version's state to new structure, if changed."""
-        if (self.data_version >= mm_cfg.DATA_FILE_VERSION and 
-                type(self.data_version) == type(mm_cfg.DATA_FILE_VERSION)):
+        """Auto-update schema if necessary."""
+        if self.data_version >= mm_cfg.DATA_FILE_VERSION:
             return
         else:
-            self.InitVars() # Init any new variables, 
-            self.Load(check_version = 0) # then reload the file
-            from versions import Update
-            Update(self, stored_state)
-            self.data_version = mm_cfg.DATA_FILE_VERSION
-        if self.Locked():
-            self.Save()
+            # Initialize any new variables
+            self.InitVars()
+            # Then reload the database (but don't recurse)
+            self.Load(check_version=0)
+            # We must hold the list lock in order to update the schema
+            waslocked = self.Locked()
+            self.Lock()
+            try:
+                from versions import Update
+                Update(self, stored_state)
+                self.data_version = mm_cfg.DATA_FILE_VERSION
+                self.Save()
+            finally:
+                if not waslocked:
+                    self.Unlock()
 
     def CheckValues(self):
         """Normalize selected values to known formats."""