diff -r b39958d6b81b -r aac4be30e250 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Thu May 03 18:39:58 2018 +0900
+++ b/mercurial/filemerge.py	Sat May 26 12:14:04 2018 +0900
@@ -724,7 +724,7 @@
                 name += ext
             f = open(name, r"wb")
         else:
-            fd, name = tempfile.mkstemp(prefix=pre + '.', suffix=ext)
+            fd, name = pycompat.mkstemp(prefix=pre + '.', suffix=ext)
             f = os.fdopen(fd, r"wb")
         return f, name