mercurial/transaction.py

--- a/mercurial/transaction.py	Thu Sep 22 21:52:00 2016 +0900
+++ b/mercurial/transaction.py	Thu Sep 22 21:52:00 2016 +0900
@@ -48,7 +48,7 @@
     for f, o, _ignore in entries:
         if o or not unlink:
             try:
-                fp = opener(f, 'a')
+                fp = opener(f, 'a', checkambig=True)
                 fp.truncate(o)
                 fp.close()
             except IOError: