diff -r 759202b64f49 -r cdbb85489c41 mercurial/error.py
--- a/mercurial/error.py	Mon Dec 01 15:04:34 2014 -0600
+++ b/mercurial/error.py	Sat Nov 29 19:13:35 2014 -0800
@@ -48,6 +48,12 @@
         Exception.__init__(self, *args)
         self.hint = kw.get('hint')
 
+class HookAbort(Abort):
+    """raised when a validation hook fails, aborting an operation
+
+    Exists to allow more specialized catching."""
+    pass
+
 class ConfigError(Abort):
     """Exception raised when parsing config files"""