diff --git a/mercurial/util_win32.py b/mercurial/util_win32.py
--- a/mercurial/util_win32.py
+++ b/mercurial/util_win32.py
@@ -183,11 +183,11 @@ def system_rcpath_win32():
     filename = win32process.GetModuleFileNameEx(proc, 0)
     return [os.path.join(os.path.dirname(filename), 'mercurial.ini')]
 
-class posixfile(object):
+class posixfile_nt(object):
     '''file object with posix-like semantics.  on windows, normal
     files can not be deleted or renamed if they are open. must open
     with win32file.FILE_SHARE_DELETE. this flag does not exist on
-    windows <= nt.'''
+    windows < nt, so do not use this class there.'''
 
     # tried to use win32file._open_osfhandle to pass fd to os.fdopen,
     # but does not work at all. wrap win32 file api instead.