--- 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"""
 

--- a/mercurial/hook.py	Mon Dec 01 15:04:34 2014 -0600
+++ b/mercurial/hook.py	Sat Nov 29 19:13:35 2014 -0800
@@ -7,7 +7,7 @@
 
 from i18n import _
 import os, sys, time
-import extensions, util, demandimport
+import extensions, util, demandimport, error
 
 def _pythonhook(ui, repo, name, hname, funcname, args, throw):
     '''call python hook. hook is callable object, looked up as
@@ -107,7 +107,7 @@
                name, funcname, duration)
     if r:
         if throw:
-            raise util.Abort(_('%s hook failed') % hname)
+            raise error.HookAbort(_('%s hook failed') % hname)
         ui.warn(_('warning: %s hook failed\n') % hname)
     return r
 
@@ -142,7 +142,7 @@
     if r:
         desc, r = util.explainexit(r)
         if throw:
-            raise util.Abort(_('%s hook %s') % (name, desc))
+            raise error.HookAbort(_('%s hook %s') % (name, desc))
         ui.warn(_('warning: %s hook %s\n') % (name, desc))
     return r