Use shutil.copystat in copyfile().

mercurial/util.py

@@ -760,7 +760,7 b' def unlink(f):'
         pass
 
 def copyfile(src, dest):
-    "copy a file, preserving mode"
+    "copy a file, preserving mode and atime/mtime"
     if os.path.islink(src):
         try:
             os.unlink(dest)
@@ -770,7 +770,7 b' def copyfile(src, dest):'
     else:
         try:
             shutil.copyfile(src, dest)
-            shutil.copymode(src, dest)
+            shutil.copystat(src, dest)
         except shutil.Error, inst:
             raise Abort(str(inst))