support hooks written in python. to write hook in python, create module with hook function inside. make sure mercurial can import module (put it in $PYTHONPATH or load it as extension). hook function should look like this: def myhook(ui, repo, hooktype, **kwargs): if hook_passes: return True elif hook_explicitly_fails: return False elif some_other_failure: import util raise util.Abort('helpful failure message') else: return # implicit return of None makes hook fail! then in .hgrc, add hook with "python:" prefix: [hooks] commit = python:mymodule.myhook

#!/usr/bin/env python
import sys, os
from mercurial import hg

f = sys.argv[1]

r1 = hg.revlog(open, f + ".i", f + ".d")
r2 = hg.revlog(open, f + ".i2", f + ".d2")

tr = hg.transaction(open, "journal")

for i in xrange(r1.count()):
    n = r1.node(i)
    p1, p2 = r1.parents(n)
    l = r1.linkrev(n)
    t = r1.revision(n)
    n2 = r2.addrevision(t, tr, l, p1, p2)
tr.close()

os.rename(f + ".i", f + ".i.old")
os.rename(f + ".d", f + ".d.old")
os.rename(f + ".i2", f + ".i")
os.rename(f + ".d2", f + ".d")