--- a/server/session.py	Wed May 20 16:13:07 2015 +0200
+++ b/server/session.py	Tue Jun 23 10:02:41 2015 +0200
@@ -392,7 +392,7 @@
 
     def __exit__(self, exctype=None, excvalue=None, tb=None):
         assert self._open # actually already open
-        self.clear()
+        self.rollback()
         self._open = False
         self.cnxset.cnxset_freed()
         self.repo._free_cnxset(self.cnxset)