diff -r 6c55e37ba5f2 -r e9ede9b4c2f8 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Tue Feb 24 00:04:55 2015 +0900
+++ b/mercurial/localrepo.py	Wed Dec 10 18:19:49 2014 -0800
@@ -909,6 +909,8 @@
                 _("abandoned transaction found"),
                 hint=_("run 'hg recover' to clean up transaction"))
 
+        self.hook('pretxnopen', throw=True, txnname=desc)
+
         self._writejournal(desc)
         renames = [(vfs, x, undoname(x)) for vfs, x in self._journalfiles()]
         rp = report and report or self.ui.warn