Found this nice script for adding git commits to trac.

post-receive

#! /usr/bin/python
# -*- coding: utf-8 -*-
#
# Copyright (c) 2010 Grzegorz Sobański
#
# Git post receive script developed for mlabs
# - adds the commits to trac
# based on post-receive-email from git-contrib
#

import re
import os
import sys
from subprocess import Popen, PIPE, call

# config
TRAC_ENV = '/path/to/trac/env'
GIT_PATH = '/usr/bin/git'
TRAC_ADMIN = '/usr/bin/trac-admin'
REPO_NAME = '(default)'
# if you are using gitolite or sth similar, you can get the repo name from environemt
# REPO_NAME = os.getenv('GL_REPO')

# communication with git

def call_git(command, args, input=None):
    return Popen([GIT_PATH, command] + args, stdin=PIPE, stdout=PIPE).communicate(input)[0]


def handle_ref_trac(old, new, ref):
    # branch delete, skip it
    if re.match('0*$', new):
        return []

    if re.match('0*$', old):
        # create
        revspec = "%s" % new
    else:
        # update
        revspec = "%s..%s" % (old, new)

    all_branches = call_git('for-each-ref', ['--format=%(refname)', 'refs/heads/']).splitlines()
    other_branches = [branch for branch in all_branches if not branch == ref]
    not_other_branches = call_git('rev-parse', ['--not'] + other_branches)
    new_commits = call_git('rev-list', ['--stdin', '--reverse', revspec], not_other_branches).splitlines()
    return new_commits


def handle_trac(commits):
    if not (os.path.exists(TRAC_ENV) and os.path.isdir(TRAC_ENV)):
        print "Trac path (%s) is not a directory." % TRAC_ENV

    if len(commits) == 0:
        return

    args = [TRAC_ADMIN, TRAC_ENV, 'changeset', 'added', REPO_NAME] + commits 
    call(args)


# main
if __name__ == '__main__':
    # gather all commits, to call trac-admin only once
    commits = []
    for line in sys.stdin:
        commits += handle_ref_trac(*line.split())

    # call trac-admin
    handle_trac(commits)