--- a/mercurial/filemerge.py	Sat May 26 12:14:04 2018 +0900
+++ b/mercurial/filemerge.py	Sat May 26 12:20:36 2018 +0900
@@ -11,7 +11,6 @@
 import os
 import re
 import shutil
-import tempfile
 
 from .i18n import _
 from .node import nullid, short
@@ -713,7 +712,7 @@
     tmproot = None
     tmprootprefix = repo.ui.config('experimental', 'mergetempdirprefix')
     if tmprootprefix:
-        tmproot = tempfile.mkdtemp(prefix=tmprootprefix)
+        tmproot = pycompat.mkdtemp(prefix=tmprootprefix)
 
     def maketempfrompath(prefix, path):
         fullbase, ext = os.path.splitext(path)