diff -r ae7a614a6a57 -r 7197812e8d44 mercurial/error.py
--- a/mercurial/error.py	Mon Jan 12 10:59:08 2009 -0600
+++ b/mercurial/error.py	Mon Jan 12 11:09:14 2009 -0600
@@ -33,3 +33,16 @@
 
 class CapabilityError(RepoError):
     pass
+
+class LockError(IOError):
+    def __init__(self, errno, strerror, filename, desc):
+        IOError.__init__(self, errno, strerror, filename)
+        self.desc = desc
+
+class LockHeld(LockError):
+    def __init__(self, errno, filename, desc, locker):
+        LockError.__init__(self, errno, 'Lock held', filename, desc)
+        self.locker = locker
+
+class LockUnavailable(LockError):
+    pass