--- a/mercurial/error.py Wed Jan 21 16:35:09 2015 -0500
+++ b/mercurial/error.py Fri Feb 06 00:55:29 2015 +0000
@@ -141,3 +141,11 @@
def __init__(self, filename, node):
from node import short
RevlogError.__init__(self, '%s:%s' % (filename, short(node)))
+
+class CensoredBaseError(RevlogError):
+ """error raised when a delta is rejected because its base is censored
+
+ A delta based on a censored revision must be formed as single patch
+ operation which replaces the entire base with new content. This ensures
+ the delta may be applied by clones which have not censored the base.
+ """