--- mailbox.py.orig	2006-11-12 12:38:00.000000000 +0000
+++ mailbox.py	2006-11-12 14:12:28.000000000 +0000
@@ -4,6 +4,10 @@
 
 # Notes for authors of new mailbox subclasses:
 #
+# To implement different locking requirements, override the
+# _acquire_lock() and _release_lock() methods, as these are used
+# internally during mailbox operations.
+#
 # Remember to fsync() changes to disk before closing a modified file
 # or returning from a flush() method.  See functions _sync_flush() and
 # _sync_close().
@@ -179,6 +183,14 @@
         """Write any pending changes to the disk."""
         raise NotImplementedError('Method must be implemented by subclass')
 
+    def _acquire_lock(self, f, dotlock=True):
+        """Lock file f using lockf and dot locking."""
+        _lock_file(f, dotlock)
+
+    def _release_lock(self, f):
+        """Unlock file f using lockf and dot locking."""
+        _unlock_file(f)
+
     def lock(self):
         """Lock the mailbox."""
         raise NotImplementedError('Method must be implemented by subclass')
@@ -553,13 +565,13 @@
     def lock(self):
         """Lock the mailbox."""
         if not self._locked:
-            _lock_file(self._file)
+            self._acquire_lock(self._file)
             self._locked = True
 
     def unlock(self):
         """Unlock the mailbox if it is locked."""
         if self._locked:
-            _unlock_file(self._file)
+            self._release_lock(self._file)
             self._locked = False
 
     def flush(self):
@@ -604,7 +616,7 @@
         self._toc = new_toc
         self._pending = False
         if self._locked:
-            _lock_file(self._file, dotlock=False)
+            self._acquire_lock(self._file, dotlock=False)
 
     def _pre_mailbox_hook(self, f):
         """Called before writing the mailbox to file f."""
@@ -804,14 +816,14 @@
         f = _create_carefully(new_path)
         try:
             if self._locked:
-                _lock_file(f)
+                self._acquire_lock(f)
             try:
                 self._dump_message(message, f)
                 if isinstance(message, MHMessage):
                     self._dump_sequences(message, new_key)
             finally:
                 if self._locked:
-                    _unlock_file(f)
+                    self._release_lock(f)
         finally:
             _sync_close(f)
         return new_key
@@ -828,13 +840,13 @@
                 raise
         try:
             if self._locked:
-                _lock_file(f)
+                self._acquire_lock(f)
             try:
                 f.close()
                 os.remove(os.path.join(self._path, str(key)))
             finally:
                 if self._locked:
-                    _unlock_file(f)
+                    self._release_lock(f)
         finally:
             f.close()
 
@@ -850,7 +862,7 @@
                 raise
         try:
             if self._locked:
-                _lock_file(f)
+                self._acquire_lock(f)
             try:
                 os.close(os.open(path, os.O_WRONLY | os.O_TRUNC))
                 self._dump_message(message, f)
@@ -858,7 +870,7 @@
                     self._dump_sequences(message, key)
             finally:
                 if self._locked:
-                    _unlock_file(f)
+                    self._release_lock(f)
         finally:
             _sync_close(f)
 
@@ -876,12 +888,12 @@
                 raise
         try:
             if self._locked:
-                _lock_file(f)
+                self._acquire_lock(f)
             try:
                 msg = MHMessage(f)
             finally:
                 if self._locked:
-                    _unlock_file(f)
+                    self._release_lock(f)
         finally:
             f.close()
         for name, key_list in self.get_sequences():
@@ -903,12 +915,12 @@
                 raise
         try:
             if self._locked:
-                _lock_file(f)
+                self._acquire_lock(f)
             try:
                 return f.read()
             finally:
                 if self._locked:
-                    _unlock_file(f)
+                    self._release_lock(f)
         finally:
             f.close()
 
@@ -940,13 +952,13 @@
         """Lock the mailbox."""
         if not self._locked:
             self._file = open(os.path.join(self._path, '.mh_sequences'), 'rb+')
-            _lock_file(self._file)
+            self._acquire_lock(self._file)
             self._locked = True
 
     def unlock(self):
         """Unlock the mailbox if it is locked."""
         if self._locked:
-            _unlock_file(self._file)
+            self._release_lock(self._file)
             _sync_close(self._file)
             del self._file
             self._locked = False
@@ -1057,7 +1069,7 @@
                 f = open(os.path.join(self._path, str(key)), 'r+')
                 try:
                     if self._locked:
-                        _lock_file(f)
+                        self._acquire_lock(f)
                     try:
                         if hasattr(os, 'link'):
                             os.link(os.path.join(self._path, str(key)),
@@ -1072,7 +1084,7 @@
                                       os.path.join(self._path, str(prev + 1)))
                     finally:
                         if self._locked:
-                            _unlock_file(f)
+                            self._release_lock(f)
                 finally:
                     f.close()
             prev += 1