--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cubicweb/misc/migration/3.15.0_common.py	Sat Jan 16 13:48:51 2016 +0100
@@ -0,0 +1,7 @@
+import ConfigParser
+try:
+    undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
+except ConfigParser.NoOptionError:
+    pass # this conf. file was probably already migrated
+else:
+    config.global_set_option('undo-enabled', bool(undo_actions))